I've run into this a few times, too -- seems to have something to do with the termcap info for tmux's virtual term. FWIW, I was able to work around it with 'stt

I've run into this a few times, too -- seems to have something to do with the termcap info for tmux's virtual term. FWIW, I was able to work around it with 'stty', e.g.: $ stty erase ^? to recognize DEL (ASCII 127, or ^?) as backspace. I have that in my .bashrc on a particular machine that gives me this problem...