From what I was told, Flexi is a resource hog... and if PM is running in tandem with Summa Cutter Control it will take hold of the USB port for the cutter and not release it when Cutter Control needs it.
I've has a similar issue with this and my S2160T will sit there with 'Waiting For Camera Control' on the LCD and the cut job will drop down into the Flexi Queue as if it had already cut the job (in only a few seconds), whilst hanging up the cutter.
My fix for this:
• Reset the cutter using the LCD (to avoid another autoload conniption fit when powering off and back on)
• Kill Flexi Production Manager
• Close and re-open Summa Cutter Control
• Once CC is running, re-open PM and resend the job.
Works like a champ in our case, this was recommended to us by Summa.
Hope this helps,
-N8