Hi.
I have a 2013 Hyundai Elantra and I also see the Pending Trouble Codes Alarm several times per week. When I go the Pending Codes screen, a few seconds, or a few minutes later, it says there are "no pending codes". The alarm usually happens at the moment when I lift my foot off the accelerator, and shift into neutral to coast up to a stop sign or a red light. Probably I'm doing something my Hyundai doesn't like, but If I knew the code, I'd know which behavior to stop.
Perhaps the Pending Trouble Codes alarm could display the code number with the alarm. I'm sure there's enough display space. e.g, When my RPM alarm, or any other alarm is triggered, it displays the current value of the parameter, and the limit that was exceeded.