To fix this miserable situation,

• Turn off enhanced tracking protection in Firefox
• Delete all Intuit cookies.
• Login to your Intuit account
• Select manage your Intuit Account from your account icon.
• Sign in and security
• Turn on 2FA
• Change the type of 2FA
• Turn off 2FA

The problem is now resolved

Turn off enhanced tracking protection

Settings | Privacy and security | Cookies and site data | Manage data | Delete all Intuit Cookies

Turn on two-step verification

Turn on

Enter password

Edit two-step verification

Turn on Authenticator app

Select your type of phone.

Install Authy from Twilio, add a new account, scan the QR code and enter the six digit code it generates.

Turn off two-step verification and the problem is resolved

You can turn Enhanced tracking protection back on if you like.