Using the El Capitan Contacts app, I was able to drag and drop several contacts from an Outlook account to a Google account. However, there is one contact that I am unable to drag and drop. It has a bit more information than the others did. The green plus sign does not appear when I drag this contact over the Google account, but that green plus sign does appear when I wave this contact over an iCloud account and another defunct Exchange account.
What is it about this contact that makes it different, and what can I do to drag and drop this contact from my Exchange account onto my Google account?