Thunderbolt Display Camera not working in OS Catalina 10.15.5

I have a Thunderbolt (2) display that I have been using for many years (mainly Mac mini 2012 and later 2018). Suddenly, the camera stopped working in OS Catalina. Sometimes, the camera LED light's up for a fraction of a second on startup. It used to work fine until at least until a few weeks ago.

I use a Mac mini 2018 (3.2 GHZ 6-Core, 32GB), Catalina 10.15.5 with a thunderbolt 3 -> 2 adapter.

The problem exists with all apps that would want to use the camera.

I have tried all the advices like security settings and resetting SMC, ' sudo killall VDCAssistant' etc.

The same problem arises with both my MacBook Pro 2017 15' and my previous MacBook Pro 13' mid 2014 (the latter does not require, and thus excludes a possible problem with, the thunderbolt 3 -> 2 adapter.

Remarkably: the camera DOES work fine when running Windows 10 in Bootcamp on this mini.

So, the problem seems to be related to the OS (one of the latest upgrades of Catalina?)

When starting VMware, I get a warning that the virtual device (camera) is not connected. The camera is simply not 'visible' for any software under OSX since very recently.