Its always a special feeling when you have a problem, search for it online, find someone with the EXACT same problem, find that it was 5 years ago and that there was never a solution, and find that you were the one with the problem five years ago.
So for the NEXT time I search for this exact same problem, i am documenting what we did this time.
We found that for some unknown reason, the main program on the robot was switching from the "Running" state to the "Paused" state. The way our line is set up, we only transmit the UOP "Running" signal to the PLC, not the "Paused" signal. Because of this, the PLC only saw that the program was NOT "Running", and attempted (repeatedly) to make it run.
However, because the program was "Paused" and not "Aborted", the robot could not accommodate the new run request, and gave the two errors. SYST-011 (Failed to run task) and SYST-208 (Feature not supported), the feature being the ability to run two instances of the same program at the same time on the same robot.
The real problem is whatever is causing the robot to enter the "Paused" state (still unknown). However one of our techs found a forum post somewhere that suggested entering a controlled start followed by a cold start to, supposedly, defragment the memory.
Whatever this ACTUALLY did, it seemed to work. The issue has not re-occurred for two days now.
I would still love to know, what can cause a robot running in auto to enter the "Paused" state, and is there a simple way to un-pause it?