Welcome to the Community space, Katy. To help me narrow this down, what’s the name of your bank, and are you seeing a specific error code? Also, have you tried manually updating your transactions?
If you haven't, you can click the Update button in the upper-right corner of the Bank transactions page. This forces a fresh pull of data and often fixes missing transaction issues. Sometimes bank feeds can get out of sync, even though they’re supposed to update automatically.
If that doesn't work, your bank connection may have expired. Check the connection status, as QuickBooks won’t import new transactions until you reconnect and give consent again. Any transactions during the disconnection might have been missed, but you can recover them by reconnecting within the right date range.
If you're in a hurry, you can always manually upload a CSV file from your bank to get those transactions in immediately.
If you have any additional questions, please feel free to reply below.