[BUG] From tmux within SSH session, `clipetty-kill-ring-save` does not send to system clipboard

[jokem59]

Describe the bug When I SSH onto my Amazon Linux instance. If I open terminal emacs WITHOUT a tmux session, clipetty-kill-ring-save works as intended and sends the region to my system clipboard.

From that same SSH session, if I launch tmux and open terminal emacs, clipetty-kill-ring-save does not send anything to the system clipboard. I don't see anything in the *Messages* buffer that indicates any error. toggle-debug-on-error also doesn't trip anything.

This was working prior and I'm unsure what changed (no changes to tmux/emacs configs recently).

To Reproduce From Ubuntu 20.04 ssh to an Amazon Linux 2 instance. Launch tmux from this ssh session and launch emacs. Attempt clipetty-kill-ring-save and observe the contents are not present in the system clipboard.

Expected behavior I expect the region clipetty-kill-ring-save is called on to be available on the system clipboard.

** System Info (please complete the following information):**

• OS: Ubuntu 20.04.6 LTS, 5.15.0-92-generic
• Emacs Version: 27.2
• Terminal program: st
• Any terminal multiplexers in play: tmux 3.3a
• Local or remote (over SSH): Remote

Additional context N/A