boot device lost after last update (Windows 11 24H2)

[GKre]

I have been using my z440 since years now (on windows 11).

On 20.03.25 morning (there was a windows update the day before) i switched on the computer and got a bluescreen,

After reboot the "boot device was not accessible".

It even is no more shown in the computer's BIOS.

Also - i am not able to restore my backup - device still missing.

The boot device is an HP EX 950 NVMe located with 3 more in an HP Z Turbo Drive Quad Pro.

At first i thought the device is broken but - using an linux os i can see the device and even the partitions. Only accessing the bitlocker partition did not work but this is a "tool issue".

Step by step i did a reset on TPMm and  at the end switched back to BIOS factory defaults.

Still the device is missing on windows and in bios (boot order menu) but shown in linux.

Next i though it is a problem with "secure boot" and i switched off this feature. Now the device is shown again even in BIOS. But still i can not access in my recovery software.

I finally removed all partitions with linux and setup a simple FAT32 partition.

Still the same. Device not visible if secure boot is enabled.

What is strange also: without secure boot i can see detailed info about the slot of the four NVMe's in the QUAD Adapter.
With secure boot enabled i see only 3 of them and a "pound sign" instead of the slot number.

So - i think that the update changed something in "secure boot" but i have no idea how to reset this to factory defaults.

--> Any help is valuable.

Meanwhile i will test kubuntu as an alternative as i am quite sure that microsoft is the cause of all my problems 😞

[GKre]

just in case it will help someone else. I did not find the root cause but i think it might have something to do with UEFI and/or secure boot.
After removing all partitions from the device i was able to install kubuntu without any problem.

Unfortunately it could not convince me to stay so i again tested my recovery media. And - big surprise - now the device was visible and i could restore without problems.

Maybe i will find a hint about the cause but for the moment i am happy to have my workstation back.