im currently creating an app with different screens based on their use cases. Nearly every screen is using a dropdown field with a generated set of elements (Option Set) to choose from. We are using the common data service, which is actualy working for the other screens but when I recently added new dropdown fields to the forms neither of them would show any item.
The dropdowns in the other screens are working fine but I can't get a new one running. I generated for this purpose a new screen to show the behaviour. Hope someone has a explanation for this.
I made a test on your issue. The issue is confirm on my side.
It seems that powerapps does not recognize the data source name as a data source table.
I find a similar issue with your issue.
please refer as: