There is a problem with clipping next item. Previously I thought it was only appearing in editor, but I've just found out that it can happen also on the screen.
Anyway, when I set a shape for clipping next object, and that object has a formula animation, which makes it dissapear in certain conditions, the clipping affects next visible object. In this case it happens only in editor.
The other scenario is when the clipping object has a formula in layer visibility field, in this case clipping also goes to next object, but this time both in editor and screen.
Here is a simple example of the second case:
https://dl.dropboxusercontent.com/u/64079193/mask_problem.klwp