Casio released an instructional video that addresses what to do if you have a problem with your Connected smartphone app crashing with Android 9 or 10. This applies to all Casio “Connected” apps for all brands and editions including G-Shock, MR-G, Baby-G, Edifice, Pro Trek, and Oceanus.
The video states that the OS Settings in “Battery” or “App Notifications” could be the cause.
It says to change the settings of the Connected app in the “Settings” > “Apps” section.
Under “Battery,” deactivate “Background Restriction.” Also, under “Battery Optimization,” deactivate “Battery Optimization” for the app.
Under “Notifications,” activate “Show Notifications.”
For the complete instructions and a visual guide, watch the video.