Error msg when starting eM Client

I have suddenly started getting the following error message when I start eM Client. I don’t know which contact is causing the problem. It tells me that contact must always be in at least one contact group. How can I determine which contact is not in the group?

[Google Contacts]Uploading item(s) to folder ‘[email protected]/Contacts’ failed due to the following error: Can not remove all contact group memberships. Contact must always be in at least one contact group.

[Google Contacts]Uploading item(s) to folder ‘[email protected]/Contacts’ failed due to the following error: Can not remove all contact group memberships.

Go to the Contacts section of eM Client.

“Right-click” on the Gmail Contacts folder, and then click “Properties” at the bottom. Then click the “Repair” tab at the top, & lastly “click Repair”.