I had this general masking technique that I used with Motion 4 where I'd use any group of shapes, paintstrokes and so on, to mask some other object by dragging my group of "mask objects" into the image mask source well.
This technique no longer works as expected with Motion 5.
As an example, consider this project where I want to gradually reveal a circle.
Below are screen shots from both Motion 4 and Motion 5 of the same project, at frame 10:
As you can see, Motion 4 gradually unveils the masked shape (a circle), but Motion 5 doesn't.
I could get around this particular case by adding a write on behaviour to the circle shape. BUt this does not work as a general masking technique in M5, which is a bit sad.
Anyone care to shed some light?