When the same contact repeatedly fails with a match or connection error, it's usually being overwritten by an outside system your contacts are linked to. The external sync rewrites the record and strips the role Gigwell assigned it, so Gigwell can no longer match it to the right place.
Clear it yourself first
Work out which outside system your contacts are synced to — a CRM, your phone, or a mail account. Knowing which one matters for the last step below.
Go to Contacts → Manage Settings → Clear Cache.
Try the contact again.
That resolves it in most cases.
If that doesn't work
If the error comes straight back after clearing the cache, this one needs our team — start a chat from the messenger and tell us which contact it is. We can re-import the record from our side, which rebuilds it cleanly.
If the error returns again after that, the external sync is overwriting the contact faster than it can be fixed. At that point the sync needs unlinking at your end — in the outside system's own settings — so it stops rewriting the record.
Good to know
If the same outside system is syncing several contacts, expect this to affect more than one of them. Unlinking the sync once usually settles all of them.
An address that changes back to an older value after you edit it is a different problem with a different fix. See the article on an email address that keeps reverting.
Clearing the cache doesn't delete anything or change your contacts. It only forces Gigwell to reload them, so it's safe to do whenever a contact behaves oddly.