I can't login on Firefox webbrowser. I keep getting the message "Please reset your password"

Please work through the list here and you should resolve it:
https://www.mixo.dj/guides/login-issues

I've tried everything. Only thing that works is Chrome browser for web login but still can't log into software

Can you login via the MIXO phone app? If so, there's clearly an issue with your desktop browser.

Did you try the code login after logging in via Chrome?