The stats site has never been good at tracking anything. PC or Console it’s nothing new this has been going on forever. Right now if you are on console for example your total XP doesn’t match XP earned by class when added up, due to a failure to track total XP for like 2 weeks. Also on console for a while you just got 0’s for everything or broken pic/link symbols. I can’t speak to how badly you all are off on PC, but it doesn’t sound like anything different.
Slightly different it also doesn’t track any match where the host leaves or gets d/c’d and I don’t know how that effects stats either. It could wind up doing something similar to what I stated concerning not tracking total XP. For example, does it track some of the stats, but not all of them in those games (I wouldn’t be surprised if this was the case).