I recently set up a WSUS Server at work to deploy updates to client workstations and ran into some common issues which I assume every IT administrator must have come across, such as clients not reporting, updates report errors, etc.
For me, the client not reporting issue was fairly simple to resolve – going to each client and manually click “check for updates”, and then the client would show up in WSUS console right away. The rest of the clients did show up eventually, it just took them sometime. And for me the wuauclt /detectnow, /reportnow, /updatenow didn’t work as fast as going to the clients and clicking “check for updates”.
Here is a very useful article that helped me along the way, highly recommended.
https://www.renanrodrigues.com/post/how-to-fix-clients-not-showing-up-in-wsus-console-step-by-step