Where did my installed themes go?

I installed [ef-themes](https://github.com/protesilaos/ef-themes) to my Doom emacs yesterday, and had been using them happily. However, loading emacs again today, I'm no longer able to access any of them via `enable-theme`. `~/.emacs.d/.local/elpa/ef-themes-0.10.0` is still there and all the themes are there.

`M-x doom/reload-packages` fixed the problem but I'm still at a bit of a loss as to why it occurred. I hope I don't need to do this every time I restart Doom.

See [Package Management](https://github.com/doomemacs/doomemacs/blob/master/docs/getting_started.org#package-management). Declare packages in `packages.el` files, then run `doom sync` from shell.