You aren't using Private Browsing mode?

• https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works, you can transfer files from a previously used profile to the new profile, but be careful not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Hello

Thanks for the reply. However,

Private browsing would not help since I am trying to clear the browsing history for sites I have already been to outside of private browsing.

This problem appeared in the last few days only. prior to that right clicking and hitting delete page in the history manager would simply delete any site selected in history. Now it has no effect.

I am not signed into a profile. There isn't one set up so any data should be stored locally. I believe it should not need to add a new profile to remove site history