I just upgraded from Ubuntu 17.10 to 18.04 (originally an Ubuntu Gnome release but that disappeared as of 17.10, right?) and my Gnome and Ubuntu desktops are un-clickable, even though the cursor moves around as usual. Everything loads up as usual, and startup apps populate. My Backups GUI comes up prompting for a password. I just can't click on anything or registering Gnome-shell-specific keyboard inputs doesn't happen. I can pull up synapse with the hot-key-combo and type in and launch apps, but that's it, and I can't use the apps since the mouse won't click and Gnome won't let me switch focus to the app. I have tried every combination of Gnome and Ubuntu DE and WM - X-org, Classic, Wayland.
This is more confounding because I previously (months ago) installed Budgie desktop to kick it's tires after getting fed up with Gnome crashes that killed the shell and kicked me back to the login screen, most predictably after several days of being open, which I ascribed to the Gnome memory leak issue boiling over. So I rebooted (I trigger graceful shutdowns over ssh under these circumstances) and logged into Budgie and mouse and at least on the surface, everything works as expected.
So I figure this is an issue with Gnome-shell, but Gnome is clearly there and running.
Anyone have suggested remedies (besides just using Budgie)?
edit: This computer is a Gigabyte BRIX (GB-BXi3-4010) with an Intel i3 4010u CPU and Intel HD-4400 Graphics.
I actually like Gnome 3 with a good compliment of extensions but all these issues with it are killing me - I'm a hair's breadth away from scrapping Gnome 3 (which now includes plain Ubuntu) but I'm so tired of hitting these roadblocks after upgrades that force me to do clean installs again and again.