Solved
Better Ladders Mod
Recently (past month) the game had been crashing to world management screen when entering live mode and I wasn't able to figure it out for a long time. Found out when trying to place a ladder then use it that it was the Better Ladders Mod.
Bryzlson Arckange's version is long broken. It's now adopted and maintained by Amethyst-Lilac. Get that version.
