I have two DL Amex Platinum cards and have had them for two years, my wife has one. Until this January my miles posted like clockwork. Amex customer service advises DL rejected my miles for Jan. and Feb. due to my name on the Amex accounts and my FF account did not match exactly. My Amex account had my middle initial and my FF account did not. They said it's been fixed but I'm still waiting for the miles to post. It appears that until this Jan. they ignored the middle initial match/doesn't match issue.
I'm also waiting for my 10,000 MQM's to post and wonder if DL will allow the MQM's for both of my cards? We exceed the $25,000 spending threshold on each of the cards, but last year DL would not allow both 10,000 mile bonuses to post as base miles. They did issue 10,000 bonus miles for each card however.