Hi there, sharonpowell.
I've checked to see if there's a reported issue about MBNA credit card connection and there's none. I suggest manually updating your bank to refresh the connection.
If the issue persists, I recommend checking your bank’s website from QuickBooks to check if the issue has something to do with your bank. Please follow these steps:
If the problem continues to occur, you'll need to manually import your credit card transaction so this entries will add to your Online banking. You can click this article on how to perform the steps: Manually upload transactions into QuickBooks Online.
Please note the transactions may re-download once the connection is fixed. If so, you'll need to exclude them to avoid duplicates. You can check this article to see the steps: Match and categorise bank transactions in QuickBooks Online.
Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.