There used to be quite a few queries about this but seemingly the issue has largely gone away. What used to be the case, and may still be at some out-stations, was that where there wasn't a fully automated data feed, Qatar would batch them up and send the information to BA once a week only, on a Wednesday morning. It could therefore take up to 3 weeks for the credit to come through, depending on the day of travel. A number of other airlines do the the same. So perhaps wait until next Wednesday and/or submit the partner claim online or call up.

If there were codeshares or other oddities, the chances of it never crediting - unless claimed by you - are much higher than flights booked into prime flights.