One or some of my tags are not autofilling anymore, and I can't add them to Help Center. They also won't autocomplete in my Support interface. I know they have already been entered into the account. What happened to these tags?
if a Tag is not used in a ticket for 60 days it will get dropped from your Zendesk Support account's indexing. You'll see this behavior in tickets, Help Center section restrictions, user profiles, and organization profiles.
Thankfully there's an easy fix to reindex the tag.
1. Go to a ticket (user profile, or organization profile) that is supposed to have a particular tag.
2. Re-add the tag by typing it into the tag field and hitting the return key!