Good day, chris124.
For now, progress invoicing is only available in the web version. Please check out this article for the complete list of features and functions that are available in the mobile app: Compare Mobile App Features.
In the meantime, use the web version so you can use the Progress Invoicing feature. We'll definitely share this feedback and will send it as a feature request to our product engineers.
Customer's suggestions and request are collected and reviewed for future updates. Let me know if you need anything else.
