Took 4 segments on Lufthansa recently. Tried to get credit on UA, UA asked me to submit my boarding passes, which I did. UA said LT said I had already received credit for the miles on LT (obviously false, I don’t have an account with LT). After submitting boarding passes and still not getting credit, United said I need to submit a copy of the ticket receipt. This sounds like a bunch of BS - why would a copy of the ticket receipt convince LT to credit the miles when the boarding passes wouldn’t? Wanted to check if other folks have had this experience or any advice. Thanks.