Why aren't transactions from my Tesco credit card coming through to QuickBooks when the account is connected?

Welcome to the Community, @usermatt-reeves-diy.

 I'll help you manually update your bank connection with QuickBooks Online to trigger updates of your bank transactions. Before doing so, make sure you can log in to your bank's website. Once logged in, take note of your login credentials.

Here's how to update the connection:

1. Log in to your QuickBooks Online account.
2. From the left menu, click Banking.
3. Select the Banking tab.
4. Choose your bank account.
5. Hit Update.
6. Click Continue.

If you're still getting the same error, download a copy of your transactions and upload them to QuickBooks Online. You can read this article for the detailed steps: Manually upload transactions into QuickBooks Online.

I'm also adding this article for future reference in categorizing transactions in QuickBooks Online: Categorise and match online bank transactions in QuickBooks Online.

Feel free to click the Reply button below if you have questions about bank connectivity. I'm always here to help. Have a great day.