Have you made sure that the tentacle sync unit & the GH5 is set to MIC level?
Sounds like the audio TC signal was distorted on the GH5 due to it being too hot.
Keep your Zooms’ tentacle on line level though, you will need Line level for BNC TC In.
You can use Tentacle Setup to adjust your output gain.
Hope this fixes your problem!
Sorry i’m late respond your answer but thanks your respond my question.
Maybe my problem is your second answer “Sounds like the audio TC signal was distorted on the GH5 due to it being too hot.” My tentacle corectly setup.
Maybe my problem to, i forgot check auto power of time. in my setup, Auto power off time is 8 hours and when we shooting i forget to restart my tentacle, my tentacle turn on all day.