On the latest beta, the undo doesn't work anymore on the main zquest. it works on tile editor, palettes, etc. but the main quest map screen.
Undo doesn't work anymore
This should be in bugs. And yeah, I noticed the same thing, but I didn't mention it for fear that someone else had already reported it. Getting rather annoying really.
yeah, I believe this was in the bug thread:
I hope it gets fixed soon!