You can double check to make sure its software and not hardware!
Hold down the power button until the Power Off option comes up.
Then, press and hold the power button again until you see the Safe Mode prompt. Click this to reboot into safe mode.
When it restarts, turn off airplane mode and make sure your phone can vibrate otherwise! (Get a text or notification, a phone call, etc), then try the app. If it works outside of the app, then its a bug concerning the app. If it doesnt work at all, then its a hardware issue.