reproduction steps:

1. open a new session of tmux
2. run tmux split-window vim
3. save the session (e.g.<prefix> C-s)
4. exit the session with tmux kill-server
5. enter a new session
6. restore the session (e.g. <prefix> C-r)

the pane containing the command is correctly restored, but the process running inside it is not. this is especially confusing when resurrect-capture-pane-contents is enabled, as it looks like the process is running, but it's not.