Posting this in case it helps someone.
On the TurboTax website sign-in page, after entering my credentials and 2FA code (which were accepted), I was taken back to the sign-in page.
I tried different 2 other browsers, and incognito/private browsing, with the same result. I even tried the mobile app, and it gave me a meaningless error: "Oops. We ran into a little bump / Let's try that again."
Solution:
Then I happened to try logging in to the main Intuit accounts site: https://accounts.intuit.com/ and it was successful, but trying to reach TurboTax from there still dumped me back to a sign-in page.
Then I remembered that I recently changed my email address in my Intuit account, and noticed that under "sign-in & security" the new email wasn't verified, so I completed the verification process, and voila, TurboTax login started working again.
Complaint:
I actually tried more things than the above, wasting 30-60 minutes. Why couldn't the website just tell me what the problem was, instead of having me guess?
If TT/Intuit support is reading - please inform your product team that it's critical to show a useful error message when the user can fix an issue themselves. The non-happy-path user experience needs improvement - you do not want to frustrate paying customers unnecessarily. Yes, I work in the software field, in case you were wondering 🙂
