I'm connecting to a remote server from Windows using a variety of ssh clients: Putty, MobaXTerm, FireSSH. I'm doing something, I don't know what, that puts me permanently in overwrite (insert) mode in all panes. Pressing the insert key doesn't fix it. It doesn't matter which ssh client I use the same thing happens. When I open a new Tmux session, all is well. But after a short time I get stuck in overwrite mode.
Could be something on the server? Or am I inadvertently hitting some strange key combination?