Does there come a time after which FB do not bother trying to resolve a retro-claim? Perhaps one month, two months etc. I have still not been retro-credited a Vietnam Airlines flight that I took in September, which I contacted the PSL about and provided them the boarding cards. I've contacted them a few times to status check but just get told about a technical issue with this flight (I cannot imagine what). I'm thinking that after a while FB just close off resolved older issues as they gain newer customer issues each day that need to be fixed.
I'd suggest you call them until you find an agent who accepts to use their superpower to manually add the missing XPs and miles to your account.
I had a similar problem this summer (KE flight, nothing happened for two months, supposedlyfor an IT problem) and eventually a PSL agent heard my story and fixed everything on the phone.