I've had issues with my last two BA trips (LHR-STR-LHR) in November and December crediting. It took about 5 days after the last flight for the November trip to credit. For December, STR-LHR took about 10 days to credit and I'm still trying to get credit for the outbound LHR-STR flight that was a week earlier.
Super frustrating, but at least enough credited to hit the 100k.