Found in Version:
The door which opens after solving the Test of Disorder appears to be closed again if you save, restart and load the game.
I use Steam version of Morrowind; TR_Mainland + TR_Travels; MGSO + couple of minor mods (Apel rain replacer + Delayed Dark Brotherhood Attack).
I understand that it may be the issue of mods incompatibility, but it's too unhandy for me to check it using only Tamriel Rebuilt. :D
Here is the video for better issue illustration: