I was having this exact issue and was hitting my head against the wall, nothing suggested online worked.
But this did:
I logged into the PC-connected VC (we have a Crestron unit and logi camera connected to a NUC running Windows 10.)
Updated to semi semi-latest version of the Graphics driver, see below.
1)Navigate to Display Adapters > Intel® UHD Graphics 630 and double click, then move to the 'Driver' tab
- Click 'Update Driver' > 'Browse my computer and select 'Let me pick from a list of available drivers on my computer
- Select version 31.xx.xxx.xxxx and click next to install. Once complete, confirm the driver version has been installed and reboot the UC-Engine.
After rebooting ( start > restart) > I was able to create a meeting > inviting the room and sharing screen which showed on both in the meeting room and online 👌🏽