M365 Shared Mailbox not synchronizing contacts V20

[Jan_Otto]

We have a few shared mailboxes. I have no problem adding them. But only some of them would actually synchronize the contacts. I'm unsure why one would sync and not the other.

 

[Charles_3CX]

Are the contacts added to the default contacts folders within these shared mailboxes? Or have any contacts folders been created manually?

 

[Jan_Otto]

The are in the default location without any subfolders created