Use Case

If you are noticing that your tags are not displaying on the frontend and the tags are still showing correctly in your tag field in the control panel entry edit it could be that the exp_tag_entry table has issues.

Possible Causes To look for

Below lists possible things that might have caused this, it is mainly just to help determain if this is happening for your site.

Possible causes for this might be: 1) Having Publisher saving entries in Draft mode vs Publish mode. 2) Updated from an older version of tag back when it used tabs instead of entry fields 3) Updated from an older EE version and then run a sync on tags (the data from exp_data_field may not have gotten out to the newer exp_data_field_x AND exp_tag_entry correctly)

How to Fix It

In EE7 Tag now includes a CLI command that will fix this automatically for you.
Simply run: php eecli.php tag:backup