Thanks for reporting problems here.
Post Jul 29, 2018 20:30
All custom tiles are upside down now.
The screenshot demonstrates the problem.

This weird effect happened in all GC maps after I upgraded to 4.1.0.
If I create a new map file and import some PNG as custom tiles, they are upside down as well.

Please help :)

Site Admin
Post Jul 29, 2018 21:26
Hi, got to Tool Opts. > uncheck "Vertical Flip."

Not sure why this happened for you without you know it, but the X and Y keys are mapped to these options by default so maybe you caught them?
Post Jul 29, 2018 22:10
David, thanks a lot!
What probably happened is me pressing Y accidentally.
I had no idea this flipping feature exists in GC.

Aaand back to mapping Ultima IV :)
Site Admin
Post Jul 29, 2018 23:23
No worries

pro-tip: You can also use X/Y to flip edges with a sided option - e.g. levers and buttons
also up/down stairs icons.