Why cant I send invoices from my phone and why has my customer list disappeared?

Hello there, @peninsulaforestr.

Let me help you perform some troubleshooting steps so you can send invoices and view the customer list in QuickBooks Online (QBO) from your phone.

Before we start, I'd like to verify if you've encountered a specific error message while sending your invoices and viewing the customer list from your phone? Any additional details will help me provide the appropriate resolution for your concern.

Based on your description, I can tell that you're sending invoices and viewing the customer list using the QBO phone app. To help us identify the cause, I would first encourage you to perform your tasks via a web browser. If you encounter the same error, you can download your invoices and manually send them to your customers' emails outside QBO.

If you're able to perform your tasks successfully via a web browser, let's go back to your QBO phone app and reset its data. This is because the QBO mobile app stores cache to speed up your experience in performing your tasks. Once it's full of cache, you'll experience errors and some unusual responses from the system. You can clear your app data to refresh the system and remove the older files that cause them.

If you're using an Android device, here's how:

1. Go to the More icon at the top right corner of the screen.
2. Choose Settings.
3. Select Refresh Data and choose Yes.

If you're using an iOS device, here's how:

1. Go to the Menu icon at the top left corner of the screen.
2. Choose Help & Feedback.
3. Select Refresh Data and Refresh.

In case the issue persists, I'd recommend uninstalling (tap and hold the app icon) and reinstalling the app. This is to ensure the version you'll be using is updated. 

Also, I'll include this article as your reference to learn more about the QBO app features available on supported mobile devices: Compare mobile app features. It contains a comparison chart between Android and iOS devices.

Let me know in the comments below how it goes. If you have other concerns about the QBO app, I'll be right here to help. Keep safe always, @peninsulaforestr.