You could try using the Plugin Check page first, to get your updates, then return to the Add-ons page to see whether that gets you to the list more speedily.

https://www.mozilla.org/en-US/plugincheck/

To update your Adobe Reader/Acrobat software, I recommend opening that software outside of Firefox and using its Help > Check for Updates feature. This will ensure that you get the right update for your product. Firefox should detect the updated plugin when you exit and restart the browser.

Any luck?

By the way, for plugins that are set to "Always Activate", website scripts can show you what you have. The ones set to "Never Activate" are not visible in the same way.

For example: https://jeffersonscher.com/res/jstest.php (scroll down...)

You can try basic steps like these in case of issues with web pages:

Reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes