With Android 5.1 and above application notifications are given a priority setting.
If you find yourself not receiving any notifications or ringtones on TextMe please change your notification priorities on your device settings.
-Go to device Settings.
-In the "Device" section select "Sound & notification"
-In "Sound & notification" scroll down and select "App notifications"
-Find TextMe in the list of applications and select it
-Set TextMe as a priority
You should now receive all TextMe notifications from then on.