I think you need to stop and read some of the above posts because it appears it is not a glitch but something that T-Mobile has change in it's account classification as to which account type can upgrade and which account type cannot.Exactly. It’s probably a glitch. But only individual regular accounts are working now. Us employee/special accounts won’t work.
Since one member put a screenshot from T-Mobile support about the possibility of account type being the problem and another member saying that account type does not appear on your account info but is something that only the reps can see on their computer system, members have been contacting T-Mobile support, getting clarification as to what their account type is and getting it changed if need be.
There is also the issue of pot luck, getting a rep who knows what they are doing. It would seem many are getting reps who know what to do and have been successful in reclassifying the account type.