Binary maps with multiple colormaps do not get converted properly to UDMF
It's a bit hard to explain, but if there are multiple colormaps in a binary map, they often get assigned the same tag in UDMF, leaving quite a mess that's hard to untangle.
According to MascaraSnake, the issue probably lies in the conversion of linedefs with action 606 in P_WriteTextMap
, where new/unused tags are supposed to be assigned. Apparently, the way this is set up will not count newly-added tags, leading to repeated assignments of the first free tag.