I'm using a current version of Neovim (0.11.4) that includes Justfile detection out of the box. If I startup Neovim with no plugins or rc file, the native detection works just fine on both Justfile and justfile. However if I load this plugin via my usual RC file and plugin manager(s), something funny happens. Now justfile is correctly detected and the ft is set to just, but if I open a capitalized Justfile, ft is empty.

Reading the code, this appears to be because the vimscript version of the ftdetect module is being run which only has the lower case variant. The Lua version seems to have all possible case versions (correct), but that version isn't getting run. I did spot a bug #124, but the upshot of that error should be that detection is always run via Lua even when the Neovim version is too old, so that doesn't explain it.

Any idea what gives?