iMessage won’t work with face id

As you all know Face ID displays your notifications when you look at your phone. It says “notification” when you’re not looking at it and then when you do it shows the actual notification. This works for everyone one of my notifications other than my iMessages. When I get a message and I’m not looking at my phone it says iMessage when I look at it and am authenticated it still just says iMessage and won’t let me preview the notification like it does for all others. How can I fix this? Please help. Thanks in advance.