Well despite every previous build being fine, this VNEXT one can't even complete install as a "kernel mode heap corruption" error BSOD occurs. Same happens whether installed from iso on HDD, SSD, or even booting the .vhdx file directly. Good job Microsoft... EDIT: And throws Virtualbox into an endless hdd-access blinky cursor death once the installer does its first reboot.
Installing in non-EFI mode as I use many OS's. Worked for the 20215 build. Just not these later ones. Looks like 20231 is due anyway.