Ya it’s hard to say. I’m not sure if these MX250 are a soldered on card or fits in a slot?
If there’s not enough power, I guess this might happen. But that doesn’t seem likely if with Windows it is working.
But some Windows feature or BIOS setting might be responsible. I guess @ricklinux is an expert on those, right?
Or is it possible that some Nvidia card jumper is set for Windows only? If you can try another linux distro (if you didn’t already), that might tell us something more.
Did you disable secure boot as i said in the images you posted of the UEFI Bios settings it is on.