This was apparently the same problem as last year. Import from husband account works fine. Then TT will not allow to import from wife account. TT remembers one account and will not allow me to sign into the other account. TT has not resolved this problem from last year. I'm going back to pencil and paper. So frustrating. TT even says, " - We don't store your credentials. That's why we ask you to enter them each time you import. Only you can access your financial information, using your own unique username and password." This is wrong. They obviously store the credentials of one account and therefore make it impossible to import from another account from the same institution.
If you have a single broker for multiple accounts, when selecting to add another account for the same broker: Clear cookies and then search for your broker via the search bar rather than clicking the broker icon. This should allow the screen to input account information and import the data.