diff --git a/resources/views/invoices/edit.blade.php b/resources/views/invoices/edit.blade.php
index 8261e6d7ae4e..b7b6e6bf5463 100644
--- a/resources/views/invoices/edit.blade.php
+++ b/resources/views/invoices/edit.blade.php
@@ -858,19 +858,14 @@
             @endif
 
             @if (isset($tasks) && $tasks)
-                // move the blank invoice line item to the end
-                var blank = model.invoice().invoice_items.pop();
                 var tasks = {!! json_encode($tasks) !!};
-
                 for (var i=0; i<tasks.length; i++) {
                     var task = tasks[i];
-                    var item = model.invoice().addItem();
+                    var item = model.invoice().addItem(true);
                     item.notes(task.description);
                     item.qty(task.duration);
                     item.task_public_id(task.publicId);
-                    item.invoice_item_type_id({{ INVOICE_ITEM_TYPE_TASK }});
                 }
-                model.invoice().invoice_items.push(blank);
                 model.invoice().has_tasks(true);
             @endif
 
@@ -878,7 +873,7 @@
                 model.expense_currency_id({{ isset($expenseCurrencyId) ? $expenseCurrencyId : 0 }});
 
                 // move the blank invoice line item to the end
-                var blank = model.invoice().invoice_items.pop();
+                var blank = model.invoice().invoice_items_without_tasks.pop();
                 var expenses = {!! $expenses !!}
 
                 for (var i=0; i<expenses.length; i++) {
@@ -894,7 +889,7 @@
                     item.tax_rate2(expense.tax_rate2);
                     item.tax_name2(expense.tax_name2);
                 }
-                model.invoice().invoice_items.push(blank);
+                model.invoice().invoice_items_without_tasks.push(blank);
                 model.invoice().has_expenses(true);
             @endif
 
@@ -1552,23 +1547,25 @@
 	{
 		var hasEmptyStandard = false;
 		var hasEmptyTask = false;
-		for(var i=0; i<model.invoice().invoice_items().length; i++) {
-			var item = model.invoice().invoice_items()[i];
+
+		for (var i=0; i<model.invoice().invoice_items_without_tasks().length; i++) {
+			var item = model.invoice().invoice_items_without_tasks()[i];
 			if (item.isEmpty()) {
-				if (item.invoice_item_type_id() == {{ INVOICE_ITEM_TYPE_TASK }}) {
-					hasEmptyTask = true;
-				} else {
-					hasEmptyStandard = true;
-				}
+				hasEmptyStandard = true;
 			}
 		}
-
 		if (!hasEmptyStandard) {
 			model.invoice().addItem();
 		}
+
+		for (var i=0; i<model.invoice().invoice_items_with_tasks().length; i++) {
+			var item = model.invoice().invoice_items_with_tasks()[i];
+			if (item.isEmpty()) {
+				hasEmptyTask = true;
+			}
+		}
 		if (!hasEmptyTask) {
-			item = model.invoice().addItem();
-			item.invoice_item_type_id({{ INVOICE_ITEM_TYPE_TASK }});
+			model.invoice().addItem(true);
 		}
 
 		if (!silent) {
diff --git a/resources/views/invoices/edit_table.blade.php b/resources/views/invoices/edit_table.blade.php
index 238cacac95a0..5d49e3a182aa 100644
--- a/resources/views/invoices/edit_table.blade.php
+++ b/resources/views/invoices/edit_table.blade.php
@@ -19,12 +19,12 @@
         <th style="min-width:32px;" class="hide-border"></th>
     </tr>
 </thead>
-<tbody data-bind="sortable: { data: {{ $isTasks ? 'invoice_items_with_tasks' : 'invoice_items_without_tasks' }}, afterMove: onDragged} {{ $isTasks ? ', visible: $root.hasTasks' : '' }}"
+<tbody data-bind="sortable: { data: invoice_items_{{ $isTasks ? 'with_tasks' : 'without_tasks' }}, allowDrop: false, afterMove: onDragged} {{ $isTasks ? ', visible: $root.hasTasks' : '' }}"
     {!! $isTasks ? 'style="display:none;border-spacing: 100px"' : '' !!}>
     <tr data-bind="event: { mouseover: showActions, mouseout: hideActions }" class="sortable-row">
         <td class="hide-border td-icon">
             <i style="display:none" data-bind="visible: actionsVisible() &amp;&amp;
-                $parent.invoice_items().length > 1" class="fa fa-sort"></i>
+                $parent.invoice_items_{{ $isTasks ? 'with_tasks' : 'without_tasks' }}().length > 1" class="fa fa-sort"></i>
         </td>
         <td>
             <div id="scrollable-dropdown-menu">
diff --git a/resources/views/invoices/knockout.blade.php b/resources/views/invoices/knockout.blade.php
index d49146e13f29..33bb56e395b3 100644
--- a/resources/views/invoices/knockout.blade.php
+++ b/resources/views/invoices/knockout.blade.php
@@ -166,15 +166,15 @@ function ViewModel(data) {
         }
     });
 
-    self.hasTasksCached;
+    self.hasTasksCached = false;
     self.hasTasks = ko.computed(function() {
         if (self.hasTasksCached) {
             return true;
         }
         invoice = self.invoice();
-        for (var i=0; i<invoice.invoice_items().length; ++i) {
+        for (var i=0; i<invoice.invoice_items_with_tasks().length; ++i) {
             var item = invoice.invoice_items()[i];
-            if (! item.isEmpty() && item.invoice_item_type_id() == {{ INVOICE_ITEM_TYPE_TASK }}) {
+            if (! item.isEmpty()) {
                 self.hasTasksCached = true;
                 return true;
             }
@@ -229,7 +229,6 @@ function InvoiceModel(data) {
     self.auto_bill = ko.observable(0);
     self.client_enable_auto_bill = ko.observable(false);
     self.invoice_status_id = ko.observable(0);
-    self.invoice_items = ko.observableArray();
     self.documents = ko.observableArray();
     self.expenses = ko.observableArray();
     self.amount = ko.observable(0);
@@ -246,17 +245,33 @@ function InvoiceModel(data) {
     self.custom_text_value1 = ko.observable();
     self.custom_text_value2 = ko.observable();
 
+    self.invoice_items_with_tasks = ko.observableArray();
+    self.invoice_items_without_tasks = ko.observableArray();
+    self.invoice_items = ko.computed({
+        read: function () {
+            return self.invoice_items_with_tasks().concat(self.invoice_items_without_tasks());
+        },
+        write: function(data) {
+            self.invoice_items_with_tasks.removeAll();
+            self.invoice_items_without_tasks.removeAll();
+            for (var i=0; i<data.length; i++) {
+                var item = new ItemModel(data[i]);
+                if (item.isTask()) {
+                    self.invoice_items_with_tasks.push(item);
+                } else {
+                    self.invoice_items_without_tasks.push(item);
+                }
+            }
+        },
+        owner: this
+    })
+
     self.mapping = {
         'client': {
             create: function(options) {
                 return new ClientModel(options.data);
             }
         },
-        'invoice_items': {
-            create: function(options) {
-                return new ItemModel(options.data);
-            }
-        },
         'documents': {
             create: function(options) {
                 return new DocumentModel(options.data);
@@ -269,7 +284,7 @@ function InvoiceModel(data) {
         },
     }
 
-    self.addItem = function() {
+    self.addItem = function(isTask) {
         if (self.invoice_items().length >= {{ MAX_INVOICE_ITEMS }}) {
             return false;
         }
@@ -277,7 +292,12 @@ function InvoiceModel(data) {
         @if ($account->hide_quantity)
             itemModel.qty(1);
         @endif
-        self.invoice_items.push(itemModel);
+        if (isTask) {
+            itemModel.invoice_item_type_id({{ INVOICE_ITEM_TYPE_TASK }});
+            self.invoice_items_with_tasks.push(itemModel);
+        } else {
+            self.invoice_items_without_tasks.push(itemModel);
+        }
         applyComboboxListeners();
         return itemModel;
     }
@@ -329,7 +349,11 @@ function InvoiceModel(data) {
     })
 
     self.removeItem = function(item) {
-        self.invoice_items.remove(item);
+        if (item.isTask()) {
+            self.invoice_items_with_tasks.remove(item);
+        } else {
+            self.invoice_items_without_tasks.remove(item);
+        }
         refreshPDF(true);
     }
 
@@ -568,18 +592,6 @@ function InvoiceModel(data) {
         }
         self.applyInclusivTax(taxRate);
     }
-
-    self.invoice_items_with_tasks = ko.computed(function() {
-        return ko.utils.arrayFilter(self.invoice_items(), function(item) {
-            return item.invoice_item_type_id() == {{ INVOICE_ITEM_TYPE_TASK }};
-        });
-    });
-
-    self.invoice_items_without_tasks = ko.computed(function() {
-        return ko.utils.arrayFilter(self.invoice_items(), function(item) {
-            return item.invoice_item_type_id() != {{ INVOICE_ITEM_TYPE_TASK }};
-        });
-    });
 }
 
 function ClientModel(data) {
@@ -769,6 +781,10 @@ function ItemModel(data) {
     self.invoice_item_type_id = ko.observable({{ INVOICE_ITEM_TYPE_STANDARD }});
     self.actionsVisible = ko.observable(false);
 
+    self.isTask = ko.computed(function() {
+        return self.invoice_item_type_id() == {{ INVOICE_ITEM_TYPE_TASK }};
+    });
+
     this.tax1 = ko.computed({
         read: function () {
             return self.tax_rate1IsInclusive() + ' ' + self.tax_rate1() + ' ' + self.tax_name1();