This is normal and it happens when the account you want to import into is already associated with a bank and routing number, or a credit card account number, for import that is different than the ones in the QBO file you're attempting to import.

To get the account to show up as an option, edit it from your chart of accounts and and then on the Bank Feed Settings tab, pick Deactivate All Online Services.

Then try importing the QBO file again and you should see the account as available to associate with your QBO file.