Custom Sound Not Playing in Notifications

My new app - built with React Native and Expo has a feature that utilizes the local notifications to display custom prescheduled notifications. Currently, the notifications are working except the custom sound is not playing. I believe there is just a configuration issue that needs to be resolved.

To bid effectively, you should:
- Have experience with React Native and Expo
- Understand local notification configurations
- Have previously built app with local notifications and custom sound

Looking forward to your proposals.