Why I can't see all my customers and transactions in my phone (android), in my PC all ok.

Let's get this sorted out, Robert.

One of the possible reasons why the customer and transactions list are missing due to a data issue within the app you are using.

When the application is not fully functional, we can perform troubleshooting steps to help fix the problem in your mobile app. This is a helpful initial step to resolve any errors.

Here's how:

1. Select the menu at the top right and choose Settings. 
2. Select Apps (the location may vary depending on your device).
3. Find the QuickBooks app from the list, then select Storage.
4. Choose the option to clear the app's data.

If the error persists, refresh your data and try uninstalling and reinstalling the app, ensure that updated security settings are downloaded, and explore enabling taxes in the account settings to resolve the problem.

Nevertheless, please check and follow the steps from the Fix other app-related issues section of this link to help you handle this matter accordingly: Fix common errors in the QuickBooks Online mobile app.

Lastly, I've added this resource to help you learn more about which features are supported on each device: Compare mobile app features.

Feel free to leave a reply if you need more assistance with accessing customer and transactions list in your QBO mobile app. I'm here to help anytime. Have a great day!