Hi,
From some time (months) midnight commander subshell functionality is not working correctly when SHELL=/bin/zsh.
Observed:
Ctrl-o hides mc panels, but no shell is loaded. Pressing any key will restore panels.
Workaround
Launch mc as
$this->bbcode_second_pass_code('', 'SHELL=/bin/bash mc ')
then everything works correctly, subshell is properly loaded.
I'm currently on
mc 4.8.27-2
zsh 5.8.1-1