Hi,
Can you please disable the plugin and then try to go to a tag archive. That way we can figure out if the plugin is causing the issue.
If the tag archives are not working even when the plugin is disabled then the issue is either with the theme or some other plugin you have active.
So the next step would be to switch to a default WP theme, if the tag archives start working it’s an issue with the theme and you’ll need to contact the theme author for support.
If it’s not working then you can switch back to the theme you are currently using and start deactivating plugins. Start with the ones that are related to tags.
Test the archive after every plugin you deactivate, after one of those it will start working and you will know which plugin is causing the issue.
