Hiya jimrock4u and thanks for the thread. I'd say the oddest thing was that the issue went away for those 100 rds and returned. Guess I'd first try cz-usa and ask to speak to one of their smiths,and if no solutions there,give Davids folks a call at cajun,as they provide technical support for their products,altho not sounding like the trigger group,but could be related to the Accu bushing in some fashion. Let us know what they sort out.
Outside chance you checked your loaded chamber indicator recently? If you bought you gun from Davids shop (CGW) they treat the end of the LCI's set screw with a drop of blue loctite,as its had a history of loosening from the threads.eventually falling out. This issue can cause the slide to not return proper,but it could also cause problems with racking thus causing your slow motion slide return issues. Its an easy fix,and if its gone,cz-usa shall ship ya the parts,hopefully not needing the gun back. Be well.