2 of 2 replaced http://apple.stackexchange.com/ with https://apple.stackexchange.com/

mc is timing out waiting for a response from bash (the shell it forks for the command line at the bottom of the screen). You can find the timeout by scrolling through the timestamps. As per man select, the system call in question waits for input on specified file descriptors. In the successful trace, FD 7 is created earlier by pipe() - it's a pipe to the child process. In the successful case I found the bash prompt jon@sonic:~$ being successfully read out of the pipe. I don't remember how I found that last, sorry.

Searching for execv confirms the pid which writes jon@sonic:~$ is bash. Then I happened to notice tmux being started somewhere in the failure case. I doubt mc likes running tmux as a shell!

You must have some sort of bash startup script which runs tmux. It avoids running it if it's already inside tmux. So mc inside tmux is fine, but not outside.

I would make sure to start tmux from a login script, not the scripts which are run for bash sub-shells. This means .bash_profile and not .bashrc. There's some information about this here which matches my thinking: https://apple.stackexchange.com/questions/71929/how-to-change-mc-midnight-command-bash-prompt-on-os-x