Rejects correct credentials in login dialog box; same prob w/Chrome and Opera

Brave v0.23.105
MacOS 12.6
Shields both on and all off

Brave rejects proven-correct credentials when attempting to connect to CommuniGate Pro communication server admin login. It WILL connect to the same server’s webmail login, with the same account info/credentials, because the latter uses direct on-screen login vice a dialog box.

Connect; credential dialog appears;
enter valid credentials;
after 5 seconds, credential entry dialog reappears.
Rinse and repeat ad nauseam; cancel, and you’re denied access.

I have the SAME problem in both Google Chrome and Opera, but not in Firefox, Safari, or iCab.

I’d post a screen shot if I could figure out how…