Could you compare that with the pop-up Cookies dialog using one of the following methods:

• right-click and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or globe icon in the address bar > More Information > "View Cookies"

In the dialog that opens, the current website will be entered at the top. If you clear that, all cookies should be shown. Anything?

If that also is blank, is it possible you are using automatic private browsing mode (in Options > Privacy > "Never remember history")? Of course, in that case, your history also wouldn't be saved...

See also:

• https://support.mozilla.org/kb/Private+Browsing

If clearing cookies didn't help then it is possible that the cookies.sqlite file that stores the cookies got corrupted.

• Rename (or delete) cookies.sqlite (cookies.sqlite.old) and delete other present cookies files like cookies.sqlite-wal and cookies.sqlite-shm in the Firefox profile folder in case the file cookies.sqlite got corrupted.

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

jscher2000 said

Could you compare that with the pop-up Cookies dialog using one of the following methods:

• right-click and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or globe icon in the address bar > More Information > "View Cookies"

In the dialog that opens, the current website will be entered at the top. If you clear that, all cookies should be shown. Anything? If that also is blank, is it possible you are using automatic private browsing mode (in Options > Privacy > "Never remember history")? Of course, in that case, your history also wouldn't be saved...

The page info displays the cookies for that page but not in the show cookies

As you've noticed, Firefox 38 introduced the tab-based Options/Preferences dialogs, and this might be a glitch with populating data into the tab for some reason (whether based on a bug in the new code or an add-on or other factor).

If you're inclined toward a little more troubleshooting, could you try Firefox's Safe Mode to see whether the cookies are visible there? Details below.

If you prefer to switch back to the old dialog instead, there is a way to do that.

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste pref and pause while the list is filtered

(3) Double-click the browser.preferences.inContent preference to switch it from true to false

Note: I don't know whether that will be in Firefox forever or is a transitional feature. As you've probably noticed, the long-term trend is to remove things that pop up.

Testing in Firefox's Safe Mode

This is a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?

To return to regular browsing, exit Firefox and start it up again without holding down the Shift key.