Audio continuously sync and desync

[Streamia.gr]

Setup:

• MacOS, OBS latest build, ATEM Mini, mini audio console connected to ATEM Mini
• x264 encoder, no filters applied on audio input

Problem description:

• Audio is synced: https://youtu.be/YEl2tmTG5zw?t=585
• Later is getting desync: https://youtu.be/YEl2tmTG5zw?t=678
• Even later, is getting re-synced: https://youtu.be/YEl2tmTG5zw?t=826
• The situation keep changing the same way.

The unique issue here, can't found in any other similar thread here, is that the problem appear and disappear without any obvious reason.

If you need any additional info, please let me know.

 

[Streamia.gr]

Watching again and again the video, I found this point where the audio is de-synced, the video is running fast-forward for a second and finally the audio is getting synced:
https://youtu.be/YEl2tmTG5zw?t=1469

Maybe this will tell something to the experienced OBS supporters.
Thank you.