After migrating my SharePoint site, I've noticed the following symptoms with my tagging feature:
-Adding new tags from a tagging field does not update my tags list
-When typing in a tag, existing tags are not suggested
-Clicking on a tag does not bring up any results
After performing a migration of your site, it might be possible that the relationship between your tags list and the connected lists that are using tags fields has been broken. In order to resolve this issue, follow these steps:
go to your tagging feature settings (site settings > top level site settings > KwizCom tagging feature management) and scroll to the bottom. You should see your list of tags list there. You will want to click on the link to bring you to your connected lists.
From there, you should see all of the lists using a particular tags collection. Due to the migration, you will notice that some of the ListId fields are blank.
For any items that are blank, you will want to open up that item and corrupt the field by entering in some random characters into the ListID field. Please note that you cannot just leave the field blank and must enter in some characters.
After doing this, save the item and then go to the list where the tagging field itself is and go to the list settings.
From there, resave the field settings. No changes have to be made.
By going back to to the list showing all lists tied to a tags collection, you should see a new entry created showing the correct ListID. The tags field should correctly work now. You can then proceed to remove the previous entry.
For your reference, the values shown in the ListID field follow the syntax of: TaggingFieldInternalName|ListGUID|SiteCollectionGUID.