Fresh install from NET 5-15/ not working in VirtualBox

After updating two real computers and a VM already running Plasma to the new KDE setup, I wanted to try a fresh install in a VM in VirtualBox to check it out that way.

First thing I notice on booting the NET install media is that the mouse integration is messed up – before these two builds, it always seemed to work correctly, however, now it was moving the cursor in the VM, but not matching the location to the actual cursor, resulting in two cursors. Turning off mouse integration fixed that.

After installation (no errors), when it got past SDDM, it just goes to a black screen. The VT’s work correctly. I narrowed it down to the vboxadd modules. I uninstalled those, and everything worked correctly (but slow). I then installed the actual ISO version of the editions, and the same thing happens – black screen after autologin.

This same setup (even using the openSUSE version) works fine in my other VM that I updated to Plasma 5.3 from 5.2, but a fresh install just won’t work.

Any debug ideas before I file a bug?