Tethered Capture will not work - I need help!

I'm running Lightroom Classic 13.4 with Camera RAW 16.4 - on a MacMini operating on MacOS Sonoma 14.5. My camera's are either a Nikon D810 or 850. For the life of me I cannot get Tethered Capture to work. On one occasion Adobe promted me to quit Lightroom 13.4 and re-start on an earlier version - and did that for me automatically - but not since. Every time I launch Lightroom then try to start Tethered Capture it will not see my camera's. What am I doing wrong? If there's an Adobe Lightroom genius out there I need your advice.

Thank you

Spence

[personal info redacted]