Getting Credit for GPU-Upgraded LH Flights
Just got off the phone with a super helpful CSR. I explained the situation and told her I heard numerous reports that simply submitting a claim is useless, and that LH would probably deny it due to the I class.
The CSR told me that the magic words to ask in the future are System Issue Form. Apparently, they need to submit such form together with the mileage request in order to get credit for a segment flown in I class, but paid for using a mileage-earning booking class. I updated the wiki accordingly.