I went like 5 for 5 early on in the program before I was rejected 21 times in a row. Finally figured out my Global Entry card, passport and drivers license all had my middle initial while my AA account did not. Added the middle initial and solved the problem....basically.
Had a situation yesterday at ORD where I went to the TSA Pre-Check lane where there were two 'code readers' out near the beginning of the line. Scanned my iPhone and showed my DL. LLL came up on the readout on the scanner and I was waved forward. At the conveyor belt there was another kiosk and TSA agent with a different scanning device. After he scanned my iPhone again I was directed into the other lane where I needed to follow the typical TSA rules and receive my full body scan, etc. More of a hassle than anything since the lines were minimal but I did receive the magic LLL code only to be rescanned 40 feet closer to the gate.
I don't understand the reason they need to scan the BP twice......