I'm not sure if this is your problem but I run into trouble with the bspwm socket not being removed after being shutdown incorrectly. Check /tmp before you run bspwm and delete the socket if it is there. `ls /tmp | grep bspwm` (I automate this with a check in my .xinitrc). Again this may not be the issue. I've never run bspwm with a DM so it's hard to say.