Why am I unable to save my invoices whenever I add shipping

Hi there, @thepartyheavenuk. I can see the importance of saving your invoices in QuickBooks Online (QBO). It's my priority to help you with the process by performing some troubleshooting steps.

To begin with, let's ensure your browser is free from the possible cache that affects QuickBooks' performance, especially when saving your invoices. For now, try to record your invoices through a private browser to see the result.

Here are the keyboard shortcuts:

• Google Chrome: press Ctrl + Shift + N 
• Mozilla Firefox: press Ctrl + Shift + P 
• Safari: press Command + Shift + N

If it works, clear the cache of your main browser to remove browser history. You can also use another supported browser as an alternative.

If you're getting the same result, I'd like to know the specific error message you've received when trying to save your transactions. This way, we can look into the error and fix it immediately.

On top of that, please ensure to add the fees correctly. An incorrect way of tracking it can affect the issue. You can learn more about the process from this article: Manually add service fees to invoices in QuickBooks Online.

If you're able to save your invoices successfully, you're now ready to receive and record invoice payments from your customers.

Let me know if you have follow-up questions while entering invoices and other transactions in QBO. I'm always here to help. Have a good one!