Yesterday I had my mobile boarding pass and it didn't have a sequence number... at the boarding the MBP scanned but also beeped.

The Gate Agent look at the MBP and realized it needed a sequence number, got into the computer typed in some command (in green dos) got the number from a long string of results, then typed it into a GUI interface to complete.
The GA definitely knew what they were doing the fix only took like 5 seconds! ^