Figured I'd update this, called AA two days after making this thread and even after deleting and adding my BA number again, it wouldn't let me pick a free preferred seat. They told me to give it a few more days. I then completely forgot about it until last night, then went to book a new flight in AA Main Cabin where it was letting me pick a free preferred seat. Looked at my flight on Wednesday afterward and it wouldn't let me get a free preferred seat still, so I called AA and had them delete and add my BA number again, and then it finally worked. So I noticed that it let me select my preferred seat 6 days after I actually got the status. Whether I had it before and didn't know I have no idea, but I noticed it last night. Problem solved though.