Can someone from the 343 Matchmaking Department please address this issue - clearly it shows on this thread that many people have lost their XP.
In my case, its very much the same. I battled stupidly hard to achieve the 30,000 XP War Games Monthly Challenge 'To the Victor Go the Spoils' (11/03/2013) while I was Rank 89. I achieved Rank 90 without achieving the 30,000 XP. As soon as I achieved the 30,000 XP I immediately boosted my rank up to Rank 94. I then came back the next day to find I was Rank 91!?!?!? ....don't know about you, but that seems to have gone down a few numbers!
Please 343, address this annoying, frustrating blow and give back the 30,000 XP...or answer with some explanation at least.
Thanks, Happy Haloing - MCD