I haven't had a chance to test this in a regular map, only PER3.

I have a solid polygon in front of the right-side door. That wall, door symbol and polygon are all one the same sheet and layer.

If I add a transparency effect to the sheet then uncheck the effect to turn it off, the polygon moves behind the door symbol.

The obvious answer is to delete the transparency effect if I'm not going to use it, but thought I'd report the bug anyway.