I bought a new Sig M11-A1 about a year ago that gave me a lot of FTE's my first two times at the range. I broke it down and cleaned it right out of the box, before the 1st range trip. Cleaned it again after the 2nd range trip. Then I noticed that the build date was like 2 years old, I called Sig for advice. The bottom line was that I realized that some of the factory lube had become like wax and it was not obvious that my first cleanings were not doing the job. But indeed that is what was causing the problem, a more thorough cleaning solved everything and I have not had any more FTE's.
If you have not already sent it to CZ, clean it and clean it again. And really get all the crevices in the rails. It might help.