Zenbook only boots to BIOS, seems to "forget" boot device

[hjheins]

System: Arch Linux
Battery or AC: both
Model: UM325AU
Frequency of occurrence: once every so many days
Reset OS: no difference
Screenshot or video:
========================
Bios seems to forget the Boot device every so often. The machine cn work for a while and boot up just fine, but out of nowhere, it will boot to the Bios. In the Bios, there is no Boot device to be found. Once I create a new one and point to the correct location on the hdd, all is fine for a while again.
Why is this happening, and how can I prevent the Bios from loosing the boot device?

thanks,

Hendrik-Jan

[hjheins]

Additional question: do you see this happening with Windows too?
I would expect so, as this seems to be a BIOS issue, not an OS issue.

[Blake_ASUS]

Hello Hendrik,
Is the hard disk, SSD or HDD from factory?
Thank you.

[hjheins]

Hello Blake_Asus,
good question. I indeed put in another M2 SSD, as the factory one only has 512Gb.
I replaced it with a Samsung 980 Pro T1b (MZ-V8P1T0BW).

thank you,
Hendrik-Jan

[Blake_ASUS]

Hello Hendrik,
Can you install the original back and see if device or BIOS is working fine?
Thank you.