I can share some insights about online banking connection in QuickBooks Online..
If you have multiple cards under one financial institution, you need to know how your bank sends the downloaded transactions before connecting them. QBO will not let you connect both a parent account and its sub-accounts.
If bank transactions needs to be downloaded to the individual accounts, you will need to connect them one at a time. This way, you will see the account balances for each register. To do that, follow the steps below:
Go to the Banking menu or Transactions menu.
Select Connect Account on the landing page, or select Add account or Link account if you've already created an account.
Find your bank from the list, or use the search bar to look for it.
After filling out all the required information, press Connect.
Another way of connecting an account is through the Chart of Accounts. Here's are the alternative steps to guide you:
Go to Accounting menu and select Chart of Accounts.
Find the account you want to connect.
Click the small arrow ▼ icon next to View register from the Action column.
Select Connect bank.
Follow the onscreen instructions.
To learn more about bank or credit card connections and other things you need to know with Banking, see the following links for reference:
I have multiple American Express cards. QBO is only showing when one them when I attempt to connect my QBO to my Amex cards.
Thank you for your comment! It turns out that the sub-card transactions are importing after all. But they are importing under the main card account. I will need to look into the deeper to see if there is a way to separate the charges so they go into the proper account in QB.