Cannot enable second virtual screen (linux guest)

[seron]

I've installed Arch linux as guest with KDE plasma desktop environment and have set the vm to provide two screens. However only one screen appears in the the screen manager kscreen. When I right click on the screen symbol in the VB status bar and select Virtual Screen 2 all resolutions are disabled and only Enable is clickable. However it doesn't get enabled and appears to do nothing.

I've got the following kernel modules loaded:

vboxvideo
vboxsf
vboxguest

I've got folder sharing and copy/paste working.

I'm pretty new to VB and multiple virtual screens and would need some guidance in troubleshooting this.

[noteirak]

Please read Minimum information needed for assistance and provide as a zipped attachment the VM log file and the guest settings.