I don't think there is compatibility issue between Fences V3 with Microsoft Windows Version 20H2. Since I am running it on my system without any issue. And, I believe, if it actually is, we will have lots more people reporting in about it.
But, we do have reports on issue with Antivirus doing something to block Fences from working properly. Could you try, uninstalling Norton 360, reboot and see if that work with Fences.
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