I have an invoice which I deleted. It still shows on the app, but not on the website. It was raised on the 07/03/22 for £40. It has no Invoice number.

Hi there, claytongidney-gm.

Thank you for visiting the QuickBooks Community. I'll be sharing troubleshooting steps to ensure that the deleted invoice will be totally removed on your QuickBooks Online app.

There are times when your QBO app has a lot of data which may cause a deleted invoice to still appear on the system. To fix this, I recommend resetting the app data to clear the cache and refresh it into its default state. 

Here's how:

1. Click Help on the navigation bar at the top.
2. Select Reset App Data.
3. Allow a moment for the process to complete. Then, close the app.
4. Be sure to right-click the app and Run as Administrator when re-opening.

If the same thing happens after performing the steps above, I suggest uninstalling and reinstalling the QBO application.

Please refer to this article to see a table list that contains different features that are supported on mobile devices: Compare mobile app features.

In the event that you have questions about this, or need anything else, you can find me here. Have a great day!