GSM Trinket

If schedules on your phone not work correctly, please perform next steps:

Samsung

• Disable battery usage optimizations

Xiaomi & Redmi

• Security (App) --> Permissions --> Autostart - Enable your app
• Settings --> Developer Options. Disable "memory optimization". To enabled Developer Options go to Settings --> About. Tap on MIUI 8 times. Full Instructions

Huawei

• Step 1: settings --> advanced settings --> battery manager --> select the app to protect it.
• Step 2: settings --> apps --> advanced --> ignore battery optimizations, select the app and ignore it.
• Step 3: settings --> notification panel & status bar --> notification center, select the app, then activate "allow notifications" and also "priority display".

Full Instructions

• Pre-EMUI 5.0 / Android 7 - Go to Settings --> "Protected apps", check your app.

Full Instructions

ASUS

• Check your app in the Auto-start Manager

Sony

• Tap on the battery icon. Go to Power Management --> STAMINA mode --> Apps active in standby --> Add your app.
• Tap on the battery icon --> tap on "Advanced" --> adaptive battery --> turn it off

Oppo

• Settings --> "Security settings" --> "Data saving" and enable your app.

OnePlus

• Go to Settings --> Battery --> Battery Optimization --> Application --> Don't Optimize

Original: documentation.onesignal.com/docs/notifications-show-successful-but-are-not-being-shown