Its most likely bolt stick. When the bolt does not completely reset, it prevents the on-off from pushing the sear forward. Since the trigger rod is connected to the sear, the trigger stays limp in the rear position.
You can fix the bolt stick issue by tuning your level 10 bolt system. Remove all the shims from the powertube first. Then install the largest carrier that does not leak with your white powertube carrier oring. Always use the same white oring for each carrier that you try. It is the oring specificly that you are adjusting. If you change orings, you need to retune. Don't put the shims back in. You won't need them.
Except for the Automag in front, its usually the man behind the equipment that counts.