fish_title displays function body instead of name after bringing to the foreground

Question

Given fish function

function nv --description 'nvim in style'
    LANG=en_US.UTF-8 ~/nvim-osx64/bin/nvim -u ~/.config/nvim/init.lua $argv
end

And fish_title:

function fish_title
    set -q argv[1]; or set argv (prompt_pwd)
    echo $argv;
end

I'd expect argv[1] being nv. Instead I'm getting function's body.

Is there any way to have function name as an argument in case of user defined functions\aliases?

PS: as the title suggests this can be reproduced only after sending the process to the background and then to the foreground with fg.