You can get transactions into your account without relying on the card connection. You can download the bank feeds through the bank's website and import them directly into QuickBooks using a CSV file. The steps below will show you how:
Go to the AMEX website, login, and then download your transactions using a CSV file.
In QuickBooks go to the Transaction tab and press the drop-down arrow beside Add Transactions.
Hit Import Transactions.
Browse for the CSV file you saved earlier and Open it.
Follow the onscreen steps, then push Let's go!
Now you'll have the missing ones from 2019 in QuickBooks. You may find this article about importing transactions helpful as well.
We currently don't have any reports of transactions not showing up from American Express. I suggest contacting them and seeing if it's a restriction, or if there's something wrong on their side with the QuickBooks connection.
Please let me know if this gets you back to business. I'll keep an eye out for your response.