Alex: I’m having the same issue where as one of my clappers recorded on seperate video cameras appear in the time line between frames !
I have an external mic on one video cam and on the other one I used an onboard mic. one vid cam with onboard mic was positioned a little closer to me that the other cam with external.
I didn’t expect a sound lag by a fraction of a second when I hit the clapper. the mics were maybe 3 ft apart one diagonal to the other.
As it turns out when I played the 2 videos back after I got them as cloe as possible I sure couldn’t tell the difference .
It just bugged me that there is no way to be “exact” with the audio sync and thus having the video “exact” also.
If you did find a way to stop the “snap to grid” in the time line let me know.
Thanks
Mark