Vm gdm login kicking me back out to login screen

Hello, I’m experimenting with nixos-rebuild build-vm-with-bootloader. I’m using a simple configuration.nix, based on the default one with a few minor changes.

It boots up to the Gnome3 login screen without any problems. But when I login, it hangs for a few seconds, then kicks me back out to the login screen. This happens with both root user and my own userid.

This seems to be a problem that has happened before in other distros and not necessarily NixOS or vm-related. But before I go testing every random fix I can find from around the internet, does anyone have any experience with this in NixOS, and know what might be causing this problem here? Hopefully it’s something simple I missed in my system config.

My configuration.nix and hardware-configuration.nix.

PS - I’ve been deleting $hostname.qcow2 before creating the vm, as detailed here.

analog behavior: