a mobile app has a timeout of 5000ms configured by default. You can adjust this setting in the app configuration by doing a manual build
If you want to trap and retry without user intervention, configure custom error handling on the REST call (custom without Rollback, for instance), and then have the error path loop back and retry the REST call. You'll want to have a counter so you don't wind up in an endless loop (retry 5 times is one I've used). This documentation will get you started with custom error handling if you haven't used that before: https://docs.mendix.com/howto/logic-business-rules/set-up-error-handling
Hope that helps,
Have you tried setting the microflow button to both synchronous and asynchronous on the mobile page? I am wondering if synchronous microflow calls are problematic on a phone platform...
Sorry I should have uploaded the Microflow. I already tried that and tested by breaking the rest endpoint. It doesn't seem to work when running in the Mendix App or even respect the Rest timeout setting too