Apparently, the issue happens when there are no security questions in the account so follow these steps:

Go to TDAmeritrade security center and log in:

https://auth.tdameritrade.com/security-center?lang=en-us

Then click on the “Two-step security preference”

Then click on “Manage Security Questions”

Fill all questions options,  should work now!

If this helped you please please consider buying me coffee!  Thanks in advance!