Things to check if the same endpoint was working before
- Check the xapi; What are the values of xStatus Audio Ultrasound and xStatus Proximity Services Availability?
- Are there any related diagnostics under Issues and diagnostics related to audio/ultrasound?
- Can other clients (Webex on desktop or mobile) or another computer running Cisco Proximity find the endpoint?
- Look in the client logs (%TEMP%\proximity-*.log) to see if anything looks suspicious...
Also, what was the version upgraded to/from? (if you know/remember the versions)