Welcome to the Community family. I can help you check why the credit card is no longer connected to your account.
Please help me identify if you're seeing an Inactive/Deleted status of your credit card. There are a few possible causes for the sudden disconnection, such as you may have accidentally disconnected it, or your bank made an update and maintenance on their end.
To verify these actions, check your Audit Log to see if someone has disabled the credit card from your account. Go to the Gear icon and select Audit Log under Tools to pull up a report.
Also, give your bank a call to get information about your concern. On the other hand, if you need to download online bank transactions, you'll have to reconnect the credit card in QuickBooks.
Go to the Banking tab.
In the Banking page, click the Add account button.
Enter for your financial institution on the search box.
Enter your User or Login ID and password for the financial institution's website and select Continue.
Complete the security verification steps your financial institution requires and select Securely connect.
Choose the bank emblem for the account you want to connect.
Select the Account type drop-down menu to choose either a Bank or Credit Card account. If you haven't already created the account, you can select +Add new to create a new account.
Also, I want to ask the name of you bank to check for any existing investigation related to your concern.
This information should help you connect the credit card to your account. Let me know how things go after following the steps above. If you have other questions aside from this, just leave a reply below. I'd be glad to answer.