Hi Pablo,
The inconsistency you are seeing between the Summary widget in Web AppBuilder Developer Edition v1.2 and the Summary application template in ArcGIS Online is a bug. Specifically, a bug in the Web AppBuilder Summary widget.
FYI, we've identified and fixed the Summary widget bug in the embedded Web AppBuilder in ArcGIS Online.
The bug fix will be included in the next Web AppBuilder Developer Edition release, v1.3. This will be likely available sometime in Dec 2015. The fix will also be included in the next Web AppBuilder embedded in Portal for ArcGIS in the 10.4 release, estimated release in Q1 of 2016.
Hope this helps,