I'm having the same problem. 

For clarity,

1. My Amex account is active in the chart of accounts

2. It is not set up in the bank feed to automatically pull transactions

3. I downloaded the QBO file from my Amex portal

4. I'm trying to import the file into my Quickbooks Desktop, but the dropdown box for existing accounts is not showing any existing account

Is this a bug in the system, and how do I fix it? Does have anything to do with user rights?