For Merrill, I saw another user changed their password for Merrill and then was able to import.
User solution:
The ultimate solution, although I do not understand why, was to change my Merrill password. Once I did this, the import worked fine. My previous password worked in Merrill, but for some unknown reason when I used the same ID/Password in TurboTax, I could not log in.. Simply changing my password in my Merrill account and then attempting the import with the new password worked.