webcam black screen mojave

I have a Logitech c229 webcam I bought 2 moths ago, on both my desktop Mac and my laptop it worked flawlessly under high Sierra. I recently updated both macs to Mojave, the c229 works flawlessly on the’ laptop, but the desktop although I the camera is a selectable option, all I see is a black screen that turns to dark grey screen in any video app that accepts an input source.

On both laptop and desktop the microphone input is fine.

killing VDCAssistant does not fix the problem, and in trying made things worse eventually impacting my iSight cameraWhich incidentally works on both devices.

could It. Be a preference file?

i have cleaned caches and that had no effect, I deleted the logitech settings from ~/library/application support/Logitech once I saw a brief video from the c229 but then it froze and I back to square one again.

any help would be appreciated.