1 hour ago, Doomofman said:
I think it's because if you hold the jump button now your character just jumps over and over again which doesn't seem like a behaviour many (if any) players would find useful
It isn't specifically that. I never hold the jump. When I couldn't get on the ladder, I was able to once I stopped pressing forward when I reached the ladder. It may be that any button being held can trigger the bug.