Updating device group for device preparation setting failed

Hello everybody,

I'm new with Intune, I just registered for 1 month free trial to play with it in a new tenant just for this demo. But I'm stuck in the beginning.

I've created a new group: https://learn.microsoft.com/en-us/autopilot/enrollment-autopilot

I also added Intune owner to this group https://learn.microsoft.com/en-us/autopilot/device-preparation/tutorial/user-driven/entra-join-device-group

Group is created without any issues.

Problem is, when I want to assign this security group to a Device preparation policy, it always ends with this error:

Failed to update device group device preparation setting
Updating device group for device preparation setting Preparation policy failed. Something went wrong.

"Preparation policy" is the name of the policy.

Creating a new group didn't help.

Thank you very much in advance for any help.

Cheers

Sislik