17.10 Upgrade – Keyboard Not Working After Login Following Upgrade from 17.04

I have just upgraded from Ubuntu 17.04 (Gnome flavor) to Ubuntu 17.10. All appears to have gone well in the upgrade, but I find after logging into either a gnome (wayland) gnome on xorg, ubuntu (wayland) or ubuntu on xorg, I lose all keyboard input. The mouse works fine, but keyboard fails to work at all. If I then logout of the session and return to gdm, the keyboard no longer works and so I cannot login to another session as I cannot enter any password.

I installed MATE and that works fine. I can login and the keyboard works fine. I also have stumpwm installed and that appears to work fine. So the problem seems to be Gnome specific either 'standard' gnome or Ubuntu flavoured gnome. Note that it was gnome I was using previously.

One other 'odd' bit of behaviour is that the main account I was using seems to have an additional session issue – when I try to log into this account, the desktop screen flashes up and then I'm returned straight back to the GDM login screen. This may be related to the fact I use zsh rather than bash as my shell on that account. I also see the same issue with keyboard e.g. once I have tried to login to that account and am returned to the gdm screen, I can no longer enter anything using the keyboard. Mouse works fine.

keyboard and mouse are both USB. This would appear to be something specific to Gnome and not related to the X server (or wayland) as other environments (stumpwm and MATE) work fine.

I did notice one other minor 'oddity'. I tried to use the on-screen keyboard. At first this seemed to be working, but then I noticed that when I tried to enter an '@' symbol, I just got a '2'. Something seems to be screwed up with input methods, but I quickly get out of my depth in this area. My region is set to English (Australia) with English (US) and English as fallbacks.

My next step will be to create a completely new/fresh account and see if that has any issues (in case the problem is due to some old gnome setting in .local, .cache .gnome etc.

Where to start to diagnose this issue?

UPDATE: I tried using a different keyboard and that seems to have resolved one problem. I can now login to a new account without loosing keyboard input for gnome or ubuntu sessions (wayland or xorg). So for some reason, the Logitech gaming keyboard I was using is not compatible with new versions of gnome (but still works fine under MATE). The replacement keyboard is an Apple aluminium USB, which seems to be working fine so far (though I have to yet verify alt/hyper etc all map correctly).

I still cannot login to accounts which existed previously with gnome or ubuntu sessions. I can login using MATE. This would seem to indicate there is something incompatible in the gnome environment beetween the gnome setup from 17.04 and 17.10. Still trying to work out what that might be.