There are some sites that have an anti-autofill feature which requires you to manually type in the username and/or password field. Usually you can click at the end, add a space, then backspace to delete the space, and that is enough for them. But some forms may be trickier.

I have not tested that specific site.

hummm....

that does not explain why Microsoft Edge works with saved passwords, and Firefox does not.

When did the problem start -- version 136 or one of its minor updates? Earlier?

Have you tried deleting the saved login and re-saving it?

I don't allow Firefox to autofill forms. Instead, I click in the field and choose from the drop-down. Not sure whether that would make any difference for you. There's a checkbox for this on the Settings page. The easiest way to find it is to type fill in the tiny search box, and then uncheck "Fill usernames and passwords automatically". (The reason I made that change is related to security, so Firefox never ever fills a form hidden somewhere on a page on its own without me having to take action.)

Interesting thought about the drop down.

But, I deleted the password and login name from Firefox. It remembered my browser, so I logged out of that. Then logged in or attempted to. Entered login name the site allowed me to go to the password enter area and entered the password. Firefox asked If I wanted it to remember it and I clicked on yes. Logged out of the site and attempted to log in with saved credentials.

Nope.

Stuck in loop.

I tried earlier to have the site send me an email to change password, but that page at the site would not respond to Firefox.

Strange problem and a valid but in compatibility to the site.

Thanks for your thoughts. Really not a big deal, just one person I like to check on in there from time to time. And this started earlier this year.