Your only option if you are unable to download your account information will be to manually enter your information.  From what you have stated in your question it appears that Pershing may be having an issue with downloading client information.

I am having a similar problem.  I can log in from TT, but it just says there is no account information to download.  It would be great if someone has a solution to share, otherwise I have about 500 lines to enter manually!

@flyty When selecting your financial institution or brokerage from the list, be sure to select the right one. For example, several participating partners' names start with First National Bank and if you select the "wrong" First National Bank, you won't be able to import. 

You may need to check your brokerage to see if they are allowing third-party access. Although the following Help Article is for Schwab, it is possible that your brokerage has restricted TurboTax's access to your statements unless you grant consent, and you might need to do something similar to what is described below: 

• How can I fix my 1099 import issue?

• Additional Import Help

• What if I can't import my 1099?

Go to your Pershing account and make sure it is set up to release information to a third party.  I have to change it for Turbo Tax every year, then I go back into my account and change it back to not allowing third party access.  If you don't see where to do that just give Pershing a call.