Shared folder between two premium account

To reproduce :
Have two "standard" paying accounts
Use the java 4.0.1 SDK
Now just use the 'AddMember' method and pass the email of the dropbox premium account you want to add to the folder.

On dropbox the folder is marked as being shared with this premium account but the user has no access to it.

The same operation works between a paid account and a free account but not between a paid account and a paid account

Example code for sharing :

public void shareFolder(UserEntity user, String folderApiId, List<String> emails) throws DbxException {
        DbxClientV2 client = getUserDropboxAccess(user);

        SharedFolderMetadata folderMetadata = getSharedFolderMetadata(client, folderApiId);

        List<AddMember> members = emails.stream().map(email -> new AddMember(MemberSelector.email(email), AccessLevel.EDITOR)).collect(Collectors.toList());

        client.sharing().addFolderMemberBuilder(folderMetadata.getSharedFolderId(), members).withQuiet(true).start();
    }