We ran into an interesting situation the other day. We were moving an active StreetSmarts system to a new server, Server 2016 or 2019 (I don’t remember which version), and the main user had a dollar sign (‘$’) in the both the Windows password and the StreetSmarts password and the login would not work.
It took us a while to figure out that the Windows password was causing the login to fail. Once we changed that password, the login worked fine.
If you upgrade to a new server, or perhaps a user login just stops working, you might look to non-alphanumeric characters in the o/s level password for a solution. We don’t know what changed, just that it did and caused the login to fail.