F11 shortcut for Full Screen mode doesn't work in Home tab on Windows desktop version (it only works in Library and Share tabs). I tested on Mac and there CTRL + CMD + F does work in Home tab. Running latest Windows and Lightroom version.
Updates to Lightroom Classic, Camera Raw, and the Lightroom Ecosystem were released yesterday and contain a fix for this issue. Please install the appropriate update and see if it solves this problem. You can read more about the updates here.