Tentacle Sync E mkII always offset by ~3 frames

Hello,

I am using a Tentacle Sync E mkII going into a Sony FX6 as well as a Sound Devices MixPre3 mkII. I have been having offset (or possibly drift) problems when trying to sync by timecode in post. Whether I use the tentacle studio app and export an XML/AAF or simply make a multicam sequence in premiere, the audio is always mismatched to video by ~3 frames. In the app, the tentacles have every indication that they are properly synced.

One possible explanation is that the timecode showing on the iphone app is not matching the timecode showing on the Sony FX6 monitor. If the app display is supposed to match the camera timecode display exactly, why might I be having this shift? The timecode settings in camera are correct:

Mode: Preset

Run: Free Run

TC Format: NDF

TC Display: Timecode

If this is not the problem, why is there an offset/drift problem here?

Edited question