Data point: BA-issued ticket, BA flight number codeshare TATL flight ex-EU on AA metal, miles posted to AAdvantage within 4 days (flown on Tuesday, miles posted Saturday). So at least BA codeshares on AA appear to post correctly. One thing I'm noticing is they're crediting lifetime flight miles according to "fare base miles", not according to the actual distance flown, so I think it's a bug.
This was outbound leg on RT ticket, with return ex-USA later this year on BA metal - hope all issues are resolved by then.