Looking into your pages HTML, it seems that the code that you made earlier copying from Tainacan Interface to try to make your theme compatible is still rendering in the Item Page, thats why you don’t see any changes. Did you make a child theme of Blocksy? Because if so, then your “tainacan/single-items.php” will replace the Support plugin one. You should not need that file, you can safely remove it if your plan is to use the Blocksy+Support plugin stack.
Giving more details, the folder that renders the item page in the Support plugin is this one:
But its logic it’s no the same of a child theme as it is a plugin instead.
Let me know if removing the previous file solved your issue, ok?