We work with two users from our Google Apps account in Zoho CRM. Till recently, we had full integration, of which the contacts synchronization is of biggest importance. 

Now, in the menu ´ Apps & Add-ons --> Google Apps --> Users´, no users are shown, nor can be added. It seems that the integration for Contacts does not work either...

We are in Professional edition. 

What has happened? What can we do about this?