OP is right, there are problems with MH crediting to AA, which I summarized here only a few weeks ago: How long to post MH miles to AAdvantage?

On all four flights I took, my Advantage number was correctly recorded in MH check-in system and it showed up on the printed boarding pass. I did finally get my miles posted, but it took more than 2 weeks for both outbound and return, and only after multiple prompts by phone and email to AA after MH said my miles had already posted to an MH account (which I've never had). I wouldn't have been so proactive had I not been counting on them for year-end status re-qual, but MH responses were annoying and incorrect. AA also said this was one of two airline partners that this is a recurring problem with.