hello dan,

follow the step and instruction:

Clear all cookies, site data and cache:

• Click the menu button. and select Options. Preferences.
• Select the Privacy & Security panel and go to the Cookies and Site Data section.
• Click the Clear Data… button. The Clear Data dialog will appear. ...
• Click Clear.

Click the Library button. , click History and then click Clear Recent History:

• Select how much history you want to clear: Click the drop-down menu next to Time range to clear to choose how much of your history Firefox will clear. ...
• Finally, click the Clear Now button.

However if the problem is not resolved then uninstall and reinstall firefox:

uninstall link step:

[https://support.mozilla.org/en-US/kb/uninstall-firefox-from-your-computer...]

reinstall link step:

https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-windows

thank you

Hello,

I discovered that the problem does not occur in Firefox Safe Mode. Try Refreshing your Browser:-

• To do this, click the menu button at the top right corner of the Firefox window.

• Click the “Help” option near the bottom of the menu.

• Click the “Troubleshooting Information” option in the Help menu.

• Click the “Refresh Firefox” button at the top right corner of the Troubleshooting Information page.

• You’ll be warned that this will remove your browser add-ons, reset your customizations, and revert other browser data to the default settings. Click “Refresh Firefox” to confirm you want to make these changes.

If it doesn't solved your problem, then feel free to ask in Reply Section. Thanks for raising your question in Mozilla Support Forum.