Hi mbutts, Check that Menu -> Options -> Privacy & Security -> Cookies and Site Data

• Delete cookies and site data when Firefox is closed

is not selected.

Also, under History - Firefox will

• Remember History

Be sure that you are not using a Private Browsing window. Cookies and Site Data, including site preferences, are not carried over to a Private window from a normal window.

In case you use "Clear history when Firefox closes" or otherwise clear history.

• do not clear the Cookies
• do not clear the Site Preferences

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

• clearing "Site Preferences" clears exceptions for cookies, images, pop-up windows, and software installation and exception for password and other website specific data
• clearing "Cookies" will remove all selected cookies including cookies with an allow exception you may want to keep

I appreciate the postings, but I already had those settings. My home laptop & desktop do not have these issues, only a Windows 10 pro machine at my office (I'm the network admin there). After the most recent Firefox update, most of this has cleared up. Still happens on some sites. This is why I have four browsers installed since every website is handled differently. Sigh.

As long as cookies & site data are not being blocked and you're sure that there is no clean-up task running from 3rd party software, like some security software has, you might want to look at this extension:

Cookie Quick Manager https://addons.mozilla.org/en-US/firefox/addon/cookie-quick-manager/?src=featured

Afterthought:

In: Menu -> Options -> Privacy & Security -> Cookies and Site Data -> Manage Permissions do you have an Exception set to Block?