I’ve had a similar issue where we flew LHR-JFK early December.
the outgoing flight ( BA flight number but on AA ) was credited almost immediately ( whilst we were in NYC )
the return leg ( on BA ) still hasnt been credited.
The Claim missing avios link using ticket number doesn’t work at all.
i have now spoken to BA 3 times about this ( after hours on hold ) - most recently on Saturday morning to a very helpful chap who logged everything again and said the TP and Avios should be credited within 7 days.