blocking access to all post/tag URIs via htaccess

I want to block all access to the post/tag/example-here pages on a WordPress site, but the following does not work. The .htaccess access file is being parsed. It is at the root of the site (ie the public_html) on a regular cPanel account. I’ve tried with and without the leading slash. I don’t understand why it wouldn’t be working.

Understanding Redirects

I have a WordPress website that is working well. The website is shared hosted on a popular hosting site. It was migrated/transferred from a different hosting site to the current one (this point is mentioned as it may play a role in the answer to these two questions). The site has an SSL on the existing site and also had one the original site. I have changed the name servers at the domain registrar to point to the new hosting site.