When I create an invoice on my iPad it does not sync to my phone. If I create a new invoice on my XR it shows up on my devices. All devices and apps up-to-date.

Thanks for visiting the Community today, @AnniesBirdGrooming. Good point on keeping your devices and apps updated. 

It looks like you're experiencing an app-related issue, this is why your iPad isn't syncing with your phone. Let's clear your app data on your iPhone to refresh the application and fix common mobile app issues. Here's how: 

1. Go to the Menu ☰ tab, then select Help & Feedback.
2. Choose Refresh Data.
3. Hit Refresh.

You can also free up the storage without deleting the documents and data by selecting Offload App within your phone settings. Here's how: 

1. Go to your phone settings, then click General.
2. Choose iPhone Storage, then choose an app that's taking up a lot of space.
3. Select Offload App to free up the storage. 

Once done, you can close and reopen the mobile app and check if it's working fine. If the issue persists, uninstall, and re-install your mobile apps to start a clean slate. Just make sure you're using the same credentials when signing back in. 

Here's an article that can help you get around with QuickBooks Online using iPad: QuickBooks Online iPad: Frequently Asked Questions. It also includes answers to your How Do I questions about using the apps. 

Feel free to message again should you have more concerns about anything else. We're always delighted to assist.