I've got steps that can help you access the receipt snap in your QuickBooks Online app, alysha.
When you can't use a feature in an app, one of the causes is the app's data. To resolve this, we can troubleshoot this issue so you can utilize this functionality again. You can refer to the steps below.
iOS
Go to Settings, then find General.
Press the iPhone Storage and tap the QuickBooks Online app.
Go to Offload App.
Android
Go to Menu, then More Options.
Locate the Settings and tap Refresh Data.
Press YES to confirm.
If the issue persists even after trying the steps mentioned, you can try deleting and reinstalling the app for a fresh start.