Room 48 is also missing. I'm not sure if it ever existed.
But I think you may be right about room 22 being cut out, since I can also see the "hourglasses."
My only guess is that they were cut out so that the game could fit cleanly onto a few disks.
Edit: I just noticed that in the disk version, the hourglasses are visible in the middle of the long exterior shot of Crystalgard (between the Chalice Room on one side and the Graveyard and Scythe Tower on the other). However, they appear to have been removed in the CD version. The artists probably felt that they should remove any indicators of the missing room from the game.
Last finished game: The DIG
Currently playing: The Secret of Monkey Island
To play list: LOOM