Well, theoretically, you should be able to switch to Wayland even when You use an Nvidia Card, but Xorg is better with Nvidia. So, it would be better to stay at it at the Moment.
If it is a big Problem that Wayland won't open/work ... In Theory not. But it depends what Issue it is and if it affects other Things.
What You could try is to reinstall the Zorin Desktop and GDM. Maybe this will resets it. If you want try this, open the Terminal and type:
sudo apt reinstall zorin-os-desktop gdm3