I now have it working on your site, at least the example you showed me of the Category view. The problem was the WP Fastest Cache plugin, which was displaying from its cache, rather than doing the WordPress processing, including my plugin, to display that Category page.
I made the following change to your test site, and encourage you to fully test my plugin's correct functioning with this setting left changed the way I have it set:
WP Fastest Cache Options
at
/wp-admin/admin.php?page=WpFastestCacheOptions
Settings tab
Cache System
Enable
uncheck box
I also deleted the Cache after that and had to refresh my browser several times before I could see the correct Theme displayed on the Category page. The browser refreshes were to empty the history on that page from my browser.