muted groupchat still shows banners imessage

I have a muted group chat but notifications still appear on my Lock Screen. I used to hide alerts on iMessage and no badges would appear on the lock screen at all. Now when I get a message from a group chat that I hid alerts on it still appears on the lock screen. Is there any way to disable this, or is it a glitch? I have no clue why if a group chat is muted it would still put notifications on the Lock Screen.