I get this same issue, on a Toshiba Portege R500 laptop with a BENQ T24IWA external monitor. Rebooting with the screen attached is the only way to get my desktop on the screen in a usable manner, and then it works perfectly. However, after doing this, I can never get my laptop screen back after a suspend, even if I switch display settings back to the laptop monitor before suspending.
I'd be happy to gather more debug info to help resolve the issue.
I get this same issue, on a Toshiba Portege R500 laptop with a BENQ T24IWA external monitor. Rebooting with the screen attached is the only way to get my desktop on the screen in a usable manner, and then it works perfectly. However, after doing this, I can never get my laptop screen back after a suspend, even if I switch display settings back to the laptop monitor before suspending.
I'd be happy to gather more debug info to help resolve the issue.