Correct some problems with setting the ondevice column values when the device is disconnected.

src/calibre/gui2/device.py

@@ -1294,7 +1294,8 @@ class DeviceMixin(object): # {{{
             self.book_db_uuid_path_map = None
             return
 
-        if not hasattr(self, 'db_book_uuid_cache'):
+        if not self.device_manager.is_device_connected or \
+                        not hasattr(self, 'db_book_uuid_cache'):
             return loc
 
         if self.book_db_id_cache is None:

src/calibre/gui2/library/models.py

@@ -125,7 +125,7 @@ class BooksModel(QAbstractTableModel): # {{{
 
     def refresh_ondevice(self):
         self.db.refresh_ondevice()
-        self.resort()
+        self.refresh(reset=False)
         self.research()
 
     def set_book_on_device_func(self, func):

src/calibre/utils/formatter_functions.py

@@ -579,10 +579,7 @@ class BuiltinOndevice(BuiltinFormatterFunction):
 
     def evaluate(self, formatter, kwargs, mi, locals):
         if mi.ondevice_col:
-            try:
-                return _('Yes')
-            except:
-                pass
+            return _('Yes')
         return ''
 
 class BuiltinFirstNonEmpty(BuiltinFormatterFunction):