I'm running Windows 11 on an Optiplex 7060. I have two internal drives which are:

* A 1TB SSD  on M2 PCie SSD - 0 which shows up as disc 1 using Windows Disc Manager

* A 1TB HDD on SATA-0 which shows up as disk 0 using Windows Disc Manager

I also have a USB connected drive, also 1TB which, when connected,  shows up as disk 2 using Windows Disk Manager.

They PC worked fine for a year or so, booting from the SSD. The HDD and USB drives contain cloned copies of the SSD for backup purposes. The USB drive is only connected when I'm doing backup cloning.

Then, last week, they system stared booting from the HDD, not the SSD, which caused some initial confusion until I figured out what was going on.

I went into the BIOS (F2) and saw that the Boot order was (1) Windows Boot Manager and (2) UEFI on the SSD. The USB drive was not connected, nut the internal HDD was, and didn't show up in the BIOS as a device.

When I changed the boot order to (1) UEFI SSD and (2) Windows Boot Manager, the PC booted from the SSD as it should have. First question - why doesn't the HDD show us as a UEFI device? Windows Disk Manager shows an EFI partition on the SSD, the HDD (and the USB) drives - as it should since they are clones. The SSD and the USB (when connected) show up as UEFI devices. Why not the HDD?

It appears that whenever Windows Boot Manager ends up being used, the HDD is the boot drive.  When the USB drive is set as #1, the SSD is set as #2 and Windows Boot Manager is #3, the boot from the USB fails with an error message "stop code inaccessible device". subsequent boots with the USB removed end up booting from the HDD again and if I go back to the BIOS, it seems that the boot order is now #1 Windows Boot Manager and #2 the SSD.

Why does the boot order change without me changing it? Does it not remember the changes I made? I've tried checking and not checking "Save as Custom User Setting", but any kind of difficulty in booting seems to move Windows Boot Manager to the top of the list, then it boots from the HDD.

I don't know where to start trying to figure out what's going on. Is at a windows 11 issue or a Bios issue. Should I need Windows Boot Manager at all. If I don't use Windows Boot manager then there seems to way to force a boot from the backup HDD drive since it's not in the UEFI list, even though it has a UEFI partition and is a clone of the SSD.

I'll stop here because too much more information might be confusing!