Domain rewrite stuck on specific user with error: "Unable to prepare <user>, a cloud source and/or on-premises target environment could not be found in Directory Sync" (4373788)

When attempting to enable Domain Rewrite for a specific user, the task gets stuck or fails with the following error message:

Unable to prepare <user@domain.com>, a cloud source and/or on-premises target environment could not be found in Directory Sync and is required to enable rewrite on a matched on-premises mailbox [UserMigrationId #<id

This issue occurs on hybrid user objects when there is an active local Directory Sync agent, but backend object mapping between local Active Directory and the cloud tenant encounters a temporary sync conflict during the rewrite preparation phase.

To resolve the state conflict and successfully enable Domain Rewrite for the user, perform the following sequence:

1. Disable Directory Sync for the affected user/environment.

2. Temporarily change the user object to cloud-only.

3. Run a Domain Rewrite Discovery task.

4. Enable Domain Rewrite for the user.

5. Revert the user object back to hybrid.

6. Enable Directory Sync again to resume normal synchronization.