I can't CTRL+I. The Raid control is integrated in my bios. I took 3 pictures from the windows control.
Here the RAID is working as expected:
And here with wrning after reboot:
In the meantime I tested some bios settings and the result is, that I have to disable the Windows Fast Boot option. If I do that, the warning vanishs and I have a stable system without RAID warnings for 2 days.