I am using Xcode 12.3 beta on Catalina 10.15.4. and i see the same behaviour in Playground. A list of 10 properties works fine, but a list of 11 will not run. and wont throw an error.

I want to do the same thing...

I ran into this problem too. If you set your padding at the top or bottom too small you see the white canvas of the widget show through. I use a view background of black for instance (using below .background attached to the greatest View). I also noticed that the Preview in Xcode and the actualy rendered widget in the Simulator are not exactly the same. One can see the corners show up in the Preview but in the simulator they are gone. I think probably the only way around this is to use a padding sufficient enough to overlap those 'gaps'. which is messy. and probably a reason why Apple has some 'design' recommendations including a padding of 15px. EDIT: I just found the way to do it. You need to include Spacer() in the VStack to stretch to max size of canvas and similarly for the HStack if you are having gaps. This solved it for me...

Did you manage to solve this ? I think you are using this in a Widget Extension?

I rebooted the iPhone. after that it was ok again.

Thanks! I have these settings: Project iOS Deployment Target = 14.4 Target App Deployment Info = 14.0 Target Widget Deployment Info = 14.4 Does the Target App Deployment Info take precedence over the iOS Deployment Target? I think the Target Deployment Version should be = iOS Deployment Target Version and not the other way around. Maybe a bug in Xcode?

Thanks. Where to file such a bug? The feedback App no one ever replies there.