I have lost many features from the mobile app including customers, mileage, invoices, estimates after I did an app update

Hello there, @JS Auto Sport. 

I can see the importance of having access to all the necessary features for managing your business on-the-go.

To isolate the issue, let's try resetting the app data to clear the cache and refresh it into its default state. Here's how:

For Android devices:

1. From More Options, then select the Settings tab. 
2. Choose the Refresh Data menu.
3. Hit Yes. 

For iOs devices:

1. Go to the Help menu.
2. Select Reset App Data.
3. Click OK.

In the Phone Settings:

• Android - 
  • Go to Settings, then select Apps.
  • Choose the QuickBooks app from the list.
  • Select Storage, then click Clear data.
• iOS 
  • Go to Settings, then choose Settings.
  • Click on General and choose iPhone Storage. 
  • Select the QuickBooks app, then click Offload App.

Once done, try to log back in and check to see if it works. If the issue persists, let's try to uninstall and then reinstall the QBO mobile app.

In addition, you may want to check out more features in the mobile app: Compare mobile app features.

Don't hesitate to get back here and reply to this post if you have follow-up questions. You can also post new questions if you need anything else in the future. We're always here to help. Stay safe!