My app has stopped saving. The message says unable to process at the moment. I've tried clearing cache, deleting app, rebooted phone and still won't work.

I want to help you save your invoices, @matthew39.

Appreciate you for trying some ways to save a transaction without an error.
 

Since you've done all of them, I'd like to confirm if you've tried saving it using a web browser? If not yet, you can try accessing your QuickBooks Online (QBO) account. From there, save the invoice.

Supported web browsers:

• Google Chrome: version 78 or newer
• Mozilla Firefox: version 76 or newer Note: To preview and print forms on Mac OS, you'll also need the Firefox PDF plugin.
• Microsoft Edge: version 75 or newer
• Safari: version 12 or newer (Mac only)

Also, I'd recommend contacting our Support Team to investigate this matter. They might open an investigation (if necessary) to resolve this issue as soon as possible. Please utilize the Help icon within your QuickBooks Online (QBO) account. 

You'll want to get more tips and information about handling sales forms:

• Email a sales form or report to multiple email addresses.
• Add, customise, or remove logos on sales forms.

I'm always around to help, matthew39. Just let me know if you need my assistance. Take care and stay safe.

Thanks for getting back.  Yes it will save when I use it online. Its just when using the app on android 

Thanks for getting back here, matthew39.

I can see that you did everything you could to fix the issue from your end. While we're unable to further investigate what's causing your app to stop saving, I recommend reaching out to our Customer Care Team. They have the necessary tools and can work with our engineers to get the app working again.

Please take note that our support hours for QuickBooks Online is available from M-F, 8:00 AM to 10:00 PM and S-S, 8:00 AM to 6:00 PM.

Here's how you can contact us:

1. Click the Help icon located in the upper right-hand corner.
2. In the Search window, click the Contact Us button located at the bottom.
3. Enter your question and click Let's talk.
4. Choose either Start a chat or Call us.

If you have the new QuickBooks Assistant help update, you can follow these steps:

1. In your QuickBooks Online account, go to the Help > Assistant.
2. Type Talk to a human and enter what do you need help with.
3. Click No if none of the articles shared are helpful and select Start a chat or Call us.

You're always welcome to post a reply on this thread if you have other concerns in your QuickBooks Online account. We're available to help you out. Take care and stay safe.