Cross-tenant mailbox migration weird error

We are running cross-tenant migration tests and run into a weird error we can't figure out.

1. We created a test Mailbox User in source tenant and populated the mailbow with a few messages and appointments.

2. We created a test Mail User in target tenant with proper attributes

3. We created a migration batch in order to move this test mailbox from source to target.

4. When we run the batch, we run into the following error :

Error: MigrationPermanentException: Source mailbox 'Tests TECHNIQUES' contains unsupported mailbox location(s) - ComponentShared. Cross tenant moves support only moving Primary mailbox, or Primary + Archive mailbox. Please remove unsupported mailbox location(s) and try again.

5. Problem is this user only have a Primary mailbox and no ComponentShared one :

MailboxLocations : {1;7f6f523c-c8ac-4321-b964-c56e46bd1876;Primary;FRAP264.PROD.OUTLOOK.COM;d5d70b4e-d1af-4a55-9550-763722395a2b}

We have really no idea where to go from there. It looks like a bug, but who knows....
Does any of you ever ran into this situation or got any idea what could be wrong ?