On the mobile version why won't let me select any suppliers when entering these expense invoices?

Welcome to the Community, userandrew. I’m here to provide fixes in selecting suppliers for expense invoices in QuickBooks Online (QBO).

We can take certain steps to eliminate common problems that may arise while using the application. To begin with, we can clear the app data to refresh it and eliminate any errors that could cause the issues mentioned above. 

To start, please ensure you're connected to the internet then perform the steps below:

Use the steps below for Android users:

1. Close and restart the app.
2. Then, clear the app data. To do so:
   • Open your device Settings.
   • Select Apps (varies by device).
   • Choose the QuickBooks app from the list, then select Storage.
   • Select clear data.
3. Power down and restart your device.
4. Uninstall and reinstall the app.

If you’re using an iOS, you can clear the app data within your phone settings, and select Offload app to free up the storage without deleting the documents and data for the app. 

Other than using the mobile app, you can also enter a billable expense by logging in to your account in your mobile or web browser. 

Please let me know if you need further assistance managing expense invoices using the mobile app. I’m always eager to help. Take care!