I've gotten credit before by submitting the BA boarding pass - one time I had to call and re-submit the boarding pass via email but have always gotten mileage credit.
Good luck
Did you include a receipt per the instructions on the website, or just the BPs?
I have a DL flight operated by AF in September, and I get the feeling that I may have to go through the BP submission process. The problem is that my receipt clearly shows that I purchased through DL with DL codes.