Mobile networks today use several different technologies to send texts. 

Some of them limit how messages are presented to Safe Lagoon and that results in them not being identified by us.

To fix this you'll need to adjust the settings on your child's telephone. 

Usually turning off Advanced messaging works.

Tap the Messages icon from the home screen
> Menu icon
> Message Settings
> Turn off Advanced Messaging. 

If you cannot find Advanced messaging you should look in the phone settings for VoLTE and turn it off.

Then restart the phone, make sure it has an internet connection and make a test text in and out. 

Check your Parent App or Safe Lagoon Portal for the text information.