Strange timecode jitter using Canon C100, Ninja V and Tentacle Sync

Hi,

I capture my video using a Canon C100 mk ii and record it via HDMI to a Atmos Ninja V. I have been struggling setting up timecode using a tentacle sync (the original, non bluetooth), but I am failing to do so.

The failing setup is connecting the tentacle sync to the mic input on the C100, then relying on HDMI to transfer this to the Ninja V. When reviewing the footage from the Ninja I see (and can hear) the timecode track. But neither Tentacle studio or Davinici Resolve are able to read the timecode data . Looking in the failrlight view in Davinci the timecode data is very, very jittery, which is probably why it fails to be interpreted correctly.

If I use the same setup and record both locally to the C100 and to the Ninja and then look at the C100 file in Davinci the timecode track is much cleaner, and its an audible difference between them. Both Davinci and Tentacle studio can identify this timecode track.

Connecting the tentacle to the Ninja directly via the mic/line input on the ninja also has a positive effect in the sense that the timecode audio looks good, and it can be read by both Davinci and Tentacle Studio.

So all in all, I am leaning on a HDMI problem with the audio. I have tested different HDMI cables, one of which being a 4k higher quality cable. That did not help. I am shooting at 1080p25 , mic level on the tentacle sync. I have tested both auto levels, manual levels and auto with attenuation on the mic input on the C100 without any difference.

So, I need some pointers, help figuring this out. I attach two images to this post, one showing the nice timecode captured from recording on the C100 SD card, the other showing TC from the Ninja with the jitter. And as I said, connecting tentacle to ninja mic input leads to the same nice curve as the C100 SD card

Any thoughts are more than welcome