@k6ccc Jim,
Thanks for the speedy reply. Yes, it is the way the pop-up screen works (which I don't fully understand). I don't have any other websites that work exactly this way, so I can't answer whether KeepassXC responds similarly. I have seen one site where the entry box isn't "open" until you click in the box, and this stumps KeepassXC. RouterOS doesn't work similarly: there is a webpage with fields to be filled in. KeepassXC handles this like a charm.
As regards "automatic signin". I don't use that feature per se. I must manually click an icon that shows on the webpage normally, and KeepassXC will fill-in the credentials. The credentials that will be filled (on click) can be verified. They must be acknowledged beforehand as appropriate for the URL (and this option can be saved). But, it doesn't auto-fill the credentials, this is an option in KeepassXC that I don't (and wouldn't) use. Yes, I can (and now must) copy and paste the credentials from KeepassXC. However, the convenience (tempered with the manual clicking on the icon) is preferred. And, so, yes, I agree, I wouldn't trust any password manager to auto-fill credentials.
I assume the problem is the popup screen for the login credentials?
Lots of systems use a popup for logging in. Do none of them work with KeepassXC?
I use a password manager, but intentionally do not use the automatic fill in the fields function. At least the PW manager I use has a copy button for any of the fields, so just copy and then paste the PW into whatever I'm logging into.