There's a very longstanding IT bug that causes some MFUed flights to incorrectly post both 0 miles and 0 tierpoints. Over the past 3 years, only one of my MFUed flights has posted correctly before having to chase down the correct postings via the local BAEC.

It would be worth knowing where you're located and if you've contacted the local BAEC about this. If you're US based, be aware that the experience level of local BAEC agents varies widely, and it's therefore often best to continue calling back until you find a knowledgeable agent that can assist you in getting the postings corrected. [The online "missing points" function at ba.com has never once fixed my MFU postings.]