My computer ASUS Z390-A BIOS version 1401
CPU i9-9900
16GB Corsair Vengeance LPX DDR4
H
as 5 internal disks 3 have the EFI boot partition.
The 850 EVO SATA SSD has a EFI boot partition and 3 bootable OS partitions.
The 970 EVO M.2 SSD has a EFI boot partition and 4 bootable OS partitions.
The 500GB WD SATA HDD has a EFI boot partition and 0 bootable OS partitions.

All 7 bootable partitions are Windows 10 Home.
6 are version latest update 1909
1 is minimal updated version 1809 for testing this problem.


When the 850 or WD are set as the boot disk in the BIOS.
You can only boot to any one of the four OS partitions on the 970 ONE time. After that you get the Boot Failed error, error “Windows Failed to start” could not find \Windows\system32\winload.efi Error Code 0xc000000e.
If you go in to the BIOS and reselect the 850 or WD the problem repeats (will boot one 1 time, next time errors).
There are NO problems booting to any of the 3 OS partitions on the 850.


When the 970 is set as the boot disk in the BIOS.
There are no problems booting to any of the 7 OS partitions