NixOS doesn't add new boot loader entries

As of the 23rd of May, it seems “nixos-rebuild switch” doesn’t add new entries (e.g. generations) to the boot loader anymore.

When I manually execute the switch, the new configuration gets loaded. But I don’t want to do this every time I boot up NixOS.

What’s going on here?

Answering my own question here for anyone who encounters this. There’s a Wiki entry that explains it. I added /boot to my fileSystems and ran nixos-rebuild boot --install-bootloader. This fixed it.