Sorry for delay
Do you have physical access to target device?
Can you check phone settings? Hoverwatch app should have Sms access permission:
If Sms permission was enabled, check this:
Open SMS app > Settings > Default sms app > is "Messaging" selected?
And check target phone settings please: "advanced messaging" setting should be turned off.
Open SMS app > Settings > Advanced messaging > disable "advanced messaging" setting.
Besides, some phones on Android 6.0 can block access to outgoing messages database. In this case you need to root target device, it will help