I purchased flights last year for my wife and I to go to CA to visit her parents last year - both on same intinerary, which typically comes through as one charge for each passenger of the exact same amount. Intially saw a hold for the total amount on my CC, then when the charge finalized and posted in a day or so only one charge came through.

Called the airline to check to make sure the tickets were valid and showing paid - twice the airline says yes (after multiple transfers around). Calls to bank and research on their end says they could only see one coming through and the one that didn't (held in suspense or not perfected by the airline). They say will probably come through at some point when they reconcile. 16 months later nothing has come through long after the flights were taken. I made every attempt to get it straight on my end.

Also a couple years ago had a cab ride in Memphis not post to my corporate AMEX till 4 months later. Was a manual reciept so likely lost in the shuffle for a while.