I'm fairly new to tmux. I tried to google a solution but no luck.
My problem is that after I (sucessfully) split my window vertically for the first time, the second attempt to split the window fails. I see the third pane for a brief second, before it closes. I then can't split it again (it just "bings" when i try). Even if i close the second pane and try to split the only window again, it just "bings". tmux kill-server sometimes help, enabling me to split a new session once. But sometimes i can kill the server multiple times and reboot, and it wont let me split. Horizontal splitting works.
I am using FreeNAS, and using FreeBSD in a jail, that I SSH into. I am using Kitty (putty) for the ssh connection.
Please help, I would really like to get more into FreeBSD/Linux, but unexplainable stuff like that really kills the mood.