The output of xrandr before suspending, after wakeup (with monitor plugged in) and finally after activating the monitor would be useful. As would the Xorg.0.log from that session, and dmesg. If you 'echo 6 | sudo tee /sys/modules/drm/paramters/debug' before suspending, then dmesg > dmesg.txt after resume attached to the monitor (and activation) would hopefully have all the information we need.
The output of xrandr before suspending, after wakeup (with monitor plugged in) and finally after activating the monitor would be useful. As would the Xorg.0.log from that session, and dmesg. If you 'echo 6 | sudo tee /sys/modules/ drm/paramters/ debug' before suspending, then dmesg > dmesg.txt after resume attached to the monitor (and activation) would hopefully have all the information we need.