First please make sure that the Admin Tools plugin is enabled and published before any other plugin.
If this didn't help, are you using caching? If you do, remember that you need to clear both Joomla!'s and your browser's cache before you see the changes. If you are using a CDN you have to invalidate the CDN content after toggling this feature.
Finally, please note that using caching and having a site which can both be accessed by HTTP and HTTPS is a very bad idea. In that case Joomla! might cache a copy of the page generated while the site is being accessed under HTTP. This means that the Admin Tools feature is not active and no link changes to HTTPS. When the site is then served over HTTPS, the cached page will be served, serving the links with the HTTP, not HTTPS, protocol. In those cases you have to either use Force SSL: All pages in the site's Global Configuration or disable cache.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!