Been following this thread with some interest.
These booking systems are transactional ones with many, many, simultaneous and near simultaneous requests to the data store. The kind of "glitches" that might occur (and I emphasize "might") would be along the lines of the unavailable access for millisecond time periods, but the software would be designed to handle these issues such that once a transaction begins, it can be completed.
What you describe is not a "glitch". It might be a bug in the software, but funny thing about bugs - they're fairly consistent in their bad behavior. Any bug such as you describe would have been seen and fixed long ago.
What you describe is user intervention, pure and simple. Someone with privileges to override the 11-month lockout rule modified the data store. Whether it was done for maintenance or some other reason of course is not known, but blaming it on some software "glitch" is just nonsense.
The most worrisome part of your story is after you started asking questions and calling for retrieval of
DVC member numbers - the "glitch" magically fixed itself.
The more I learn about DVC, the more it smells. Legally, is there any language in the contract between Disney and the DVC member that might allow this behavior? Is this the reason why Disney continues to allow unlimited walking of reservations - to provide some kind of "smoke screen" to some of their own shenanigans?