Didn't do it in a long time but maybe it has something to do with
INT of char you are using , on 2nd floor from exit some options are
not there is you are 4 or lower and you have to start so maybe
Also , when you enter , guard at door sometimes starts fight unless
you are wearing Pink Robe (which mutants can't wear).
Only other thing I can think of : Do you talk to guard or just go up
stairs and are stopped by dialogue ?