Thanks for trying to help!
So I have these mosaic pieces that are covered (=overlapped) by ground tiles [see pic].
I've set an event that supposed to cause a mosaic piece to start flashing if it is completely uncovered (=doesn't overlap ANY ground tiles)[second pic].
This works exactly as intended in the debug layout. However, in the preview layout, mosaic pieces start flashing as soon as ANY ground tiles are removed from them (even if they are still partially covered - as in the pic).
What's going on?