Ctrl + Enter "submit comment on issue" shortcut only works once when page is initially loaded

How to reproduce

1. Open an Issue page.
2. Press "m" key to open comment box.
3. Type something in comment box.
4. Press Ctrl + Enter to use "AJAX post comment" shortcut.
5. Press "m" key again to open a new comment box.
6. Type something in new comment box.
7. Press Ctrl + Enter.

Expected

Another "AJAX post comment" is fired and the comment is posted.

Actual

Nothing happens.

Summary

It appears the functionality only works when you initially load the page – i.e. you can only post 1 comment in that way for any given page load.