Do Not Disturb and text alerts

I have an iPhone 7 running 11.1.2. I want to leave my phone in DnD mode and only allow calls and texts from my contacts to alert me. The call part of it works fine. The problem is the phone doesn't alert me when a text message from a contact comes in. Is that a bug? Or is there something else I need to do to get alerts for text messages?

Thanks!

Rosy