Thunderbolt Display camera freezes during video chat

First, make sure the connection is good (either via Octopus cable or additional TB2 cable from the extra TB port).

Then: either in extended display mode or clam-shell mode..

Can you go to "About This Mac" --> "More Info.." --> "System Report" --> on the right panel "USB"

If you can see USB 2.0 and under that -- you should see "speakers" "webcam" .... etc.

If only USB 3.x appears -- likely the logic board is bad (don't forget, this device has been on the block for a while).

I have encountered many bad Logic Boards over the years -- usually symptoms are

1. flickering screen first, then lost the USB devices connected to the TB display
2. sound disappears
3. webcam stop working

Some time, if you unplug the power cable, reattach the power might get it work for short time.

After a while, it just completely be unstable..

Best

Try posting in the MacBook community? Doesn’t look like an issue with the display.

Hope so.

You might have to check it during the video call (stress test), to rule that out when you can dulicate the probelm.

Then, it might be something else from the harware point of view.

Best