I've downloaded QBO on my phone, and it shows all my invoices and expenses, but not my customers and suppliers. When I try to add a a new one it says it already exists?

Hi flatlanderscontr,

Welcome to Community!  The QuickBooks Online mobile app is a great way to work while on the go.  It's important that you're able to accomplish your QuickBooks goals with peace of mind.  I'd be happy to provide more insight here!

The QuickBooks Online Mobile app is an add-on and some of the features will vary.  Based on the information you've provided, I suggest first troubleshooting the issue by refreshing the app, or uninstalling and reinstalling it.  

Here's how to refresh the app;

For iOS;

1. Go to Menu ☰ and tap Help & Feedback and then Refresh Data
2. Tap Refresh to confirm

For Android;

1. Tap More Options from the Menu ☰

2. Select Settings and then Refresh Data

3. Click YES to confirm

If you experience the same outcome, I recommend logging into your QuickBooks Online account from a web browser.  Should the issue persists, please don't hesitate to contact us so we can look further into this from our end.

Schedule a Callback or start a Chat: click (?) Help in the upper right in QuickBooks Online > enter "Contact support" > hit Contact Us > provide a brief summary of your situation > hit Let's Talk > choose Get a callback or Start a Chat.
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Please feel free to reach back out if you have any other questions.  We'd be glad to assist!