I had a similar issue last year. After firing a few rounds, the bolt stopped cycling.
The gas block adjustment screw is set with Loctite (or similar product) at the factory
making it difficult to adjust the first time.
JP responded quickly with several suggestions. Tried all of them
and eventually was instructed to return the rifle.
A couple of weeks after the rifle was returned, a tech analyst called and I was informed that
the gas tube had ruptured and that they needed to rebuild the upper.
The rebuild took a couple more weeks.
Since being returned, the rifle is a dream.