Hi Julio, I had the same problem and rebuilt it with the template grid indeed. Works fine now.
I think is has historic reasons because now you can create editable template grids with the form loader, that wasn't always the case.
An other reason is possibly performance. Imo both widgets are not really efficient for doing this in terms of request they sent to the server. Maybe the dataview list is a bit more efficient. You can check that out by opening firebug to get an idea about the request volume the dataviewlist widget is sending to the server. After replacing the widget, check it again to see if there is substantial differenence.
The DataViewList is capable of rendering a different template for each specialization of the main entity. Unfortunately, the implementation in the App Store module does not use this feature and uses conditional formatting instead. This leads to bad performance.
For Mendix 5 users: In Mendix 5.3.1 we added inheritance and editability to the standard List View widget so that you do not need the DataViewList widget anymore.
See also my answer here: https://forum.mendix.com/questions/5997/DataViewList-widget-not-working-in-in-51