Thanks for joining this thread, @delkins.

We can perform some troubleshooting to see if this is a browser-related cause.

I'd like to start with opening a Private Window or an Incognito Window in your web browser. This will open your account in a clean slate and loads fresh data. Here's how:

• Mozilla Firefox / Internet Explorer: Press CTRL + Shift + P
• Safari: Press Command + Shift + N
• Google Chrome: Press CTRL + Shift + N

Once you're in the Private / Incognito Window, try to sign in to your QuickBooks Online account.

If it works, you can go back to your original browser and clear the cache. Alternatively, you can use other compatible browsers.

You can follow this Community Article if you need to reset your password or recover your User ID for your QuickBooks Online account: Manage Log In Credentials.

Let me know if you can get logged in successfully. I'll be here if you need further assistance. Have a great day!