Notification not showing when device is locked or app is closed.

I am trying to get notification on Android device. I am getting notification sound and notification text in status bar. But notification content is not showing when device is locked.

I am sure there is some Android setting is required but i dont' know what to do. Please help!

The report names no source file, entry point, or test. Start by reproducing the notification behavior on a locked Android device and checking the module's notification configuration and documentation; done should mean identifying whether a repository change is needed and documenting a verified resolution.

Written by the indexing model from the issue text.