We have one report that United included GIFT CERTIFICATE in the description of a Travel Bank purchase which was not reimbursed. Other posters who have reported a failure have not mentioned if their transaction included this description (and may not know where to look for it). This is a change that would have been made by the airline, not by American Express.
This is indicative of a TB purchase that was made as a gift vs one that is made for self and it was already established last year that purchasing as a gift no longer works, but purchasing for self had continued to work up until 2/5.