Hi there, chiefkeith!
Thanks for reaching out to the Apple Support Communities! It sounds like you are having an issue with the option to hide the message alerts for a group. First, I recommend checking out this article to Update your iPhone, iPad, or iPod touch. This will get your device on the latest iOS version available. Once you have updated, test to see if the issue is still going on.
If the issue is still going on, check out this article to Use Messages on your iPhone, iPad, or iPod touch to delete the conversation and have a member of the group send a response to the groups to see if you get the alert.
Let me know the results and have a great day!