Hi,
i know that i have not posted on this forum before, but i have been quietly 'lurking' in the wings.
Im almost sure that your problem stems from the fact that your gun is circa 2010, and i recall reading about firing pin problems from that time period-the newer models do not seem to have this problem anymore.
i came across this information, due to the fact that, i myself will be buying another shotgun very soon, and i have boiled it down to two Turkish models (one is the CZ 712), hence the heavy research.
So as advised, contact CZ and get it replaced.
Good luck.