Sidecar and Airplay not working

Hello,

I have an iMac 2017 running Sequoia 15.3 and Sidecar is not working wireless, only through USB-C. I get a black screen.

The same thing also happens when using Airplay transmitting to my Apple TV.

And finally I don't see my iMac when trying to mirror my iPad to my iMac.

Is this due the patch? Is there something I can do to fix it?

Thanks.