MS lost the ability to print that guarantee a few months ago. I believe Special Needs (which is part of CRO) updated their computers and MS's system is outdated. It shows up on MS' computers, or so the CMs keep telling me. I've even called Special Needs separately and confirmed the room was blocked. You can do that too, if you wish. Special Needs seems to know more about it anyway. The number is listed in the DISabilities section FAQ sticky (407-939-7807).
FWIW, the way it works is that Special Needs blocks the room at the time of booking. MS then has notations to that effect and a lock on the ressie to prevent a room assigner or Front Desk CM from mistakenly moving you to a non-accessible room.