This happened to me once in LAX, (1 out of 15) I had to go to the counter to get a boarding pass. It took 45 minutes because only 1 person behind the counter out of 10 could print a boarding pass, all the other people were just there to help people with the electronic check-in and were not authorized to print passes. The next time I went through LAX, I just went through the line with the person I thought would be the nicest, and it has worked so far.