Sorry I couldn't duplicate your problem, when my phone is in standby, incoming sms text messages awaken the screen and causes it to light up for a few seconds, with the text message showing at the top of the screen. Shortly after, the screen goes to sleep/glance mode, glance showing a text message icon below the time. Can you please verify these settings for text messages:
- Settings --> Notifications+actions --> Messaging - SIM 1 --> Show notification banner should be checked ON.
- Settings --> Glance Screen -- > Quick status notifications should be toggled ON
- Settings --> Lock screen --> Choose apps to show quick status , you should see text message icon (and maybe Whatsapp too if you like to see that)
WW