This is an error issue that Firefox users on Firefox 115 like the 115.33.0esr you appear to be using may get. Firefox 115.33.0esr is based on the old Firefox 115.0 Release but with security/stability updates since.

The UserAgent you used to post this thread is Mozilla/5.0 (Windows NT 6.2; Win64; x64; rv:109.0) Gecko/20100101 Firefox/115.0

Now you say you have Windows 10 and when I see UA's with Windows 8 and not 7 or 8.1 it is usually because they were running Firefox in Windows 8 compatibility mode for some reason.

After unchecking run Firefox in compatibility mode, if you then do an internal Firefox update you will likely get updated to the current Firefox 140.8.0esr. If you prefer to have the current Firefox 148.0.2 Release then see https://www.firefox.com/download/all/

I've messed with this for days following all the online suggestions. Should have come to you right away! This solved my problem. Thanks so much for your prompt and helpful reply. Blessings,

Sorry I forgot a link on how to uncheck run in compatibility mode on Windows 10 though it seems you figured that out.

Feel free to ask a question like this early on as I have seen many cases where people asked such a question only to come back a bit later and say they figured out the cause and fix and and say what it was if nobody replied before then.