It is not, in fact, a multi-year bug. While there was a bug about a year ago that affected only the cosmetic helms, there was a new bug that came about with 9.1 that borks out all store-bought and RAF mogs. There is not a fix or work-around as yet, but it is very well-documented and they are working to try and figure out how and why it’s happening. Your mogs will come and go without rhyme or reason, but you still own all of them.
There are a few posts from one of our SFA Blues touching base to acknowledge the issue and all of that in this thread.