Strange drift Sony FX6 Zoom F4
I used a Sony FX6 and a Zoom F4 recorder. Both had a Tentacle attached permanently. FPS was set to 29,97 on all devices. Sequence in premiere is also at 29,97. Syncing TC in post gave serious trouble and I ended up syncing with audio instead of TC. Looking at my sequence I now see that whenever there is a new audio or video clip, audio is behind by 1 frame, but this difference becomes larger quite quickly and after ten minutes audio is like over 20 frames behind (with both clips running normally at 100% and no cuts). Does anybody have any idea, how a clip that starts out in sync (well, nearly) can be out of sync (according to TC) by the end of it?
@Fokke, I made some more Tests. After jamming the FX6 with a Tentacle, I disconnect both. After more than 4 Hours, the 1 Frame Offset is the same. Seems to be a pretty good TC Generator in the FX6. I wrote to Tentacle Sync. They answer: It seems more than a Bluetooth related thing and not a real Problem with Frame-accuracy.
@Dieter; If the drift is constant, we call it an offset. Drift is always drifting….meaning the offset gets more and more.
Although i think tentacle makes great solid products and know what they are doing, i still am not 100% sure the TC reader app shows the correct timecode on every iPhone.
@svalk, i think so too that there is a framerate issue ging on here.
I found out, that there is a drift between the TC from the Tentacle an the recorded TC. The Tentacle is connected to the FX6 permanently and when I film the Timeslate App and use the TC-Effect from FCPX, there is a drift of 1 Frame. After 1 Hour, there is no additional Drift, the 1 Frame is consistent. 
I figured it must me a DF non DF issue. Normally as a European I shoot in 25p and life is simple, but here we had an American client requesting a different frame rate. My bad.