I noticed that some members of the community have encountered the same problem recently, and I can also reproduce the problem locally. The
Prefer: IdType="ImmutableId request header may no longer be available, I suggest you open a support ticket to confirm with the team. You can raise support ticket from:
http://aad.portal.azure.com or https://admin.microsoft.com/#/support/requests.
Hope this helps.
If the answer is helpful, please click Accept Answer and kindly upvote. If you have any further questions about this answer, please click Comment.