Get iMessage Text, But Not Notification Sound

I have an 2nd gen iPhone SE (running iOS 14.4) and have an unusual issue with not getting the message notification sound for just one sender. I get their actual text message, but not the notification sound. For phone calls, they come through with the correct ring tone. Not sure how long this has been an issue, but I'm pretty sure it has nothing to do with the latest iOS update. I do not have this issue with any other sender.

What I have already checked/done:

• Mute phone switch checked to make sure it was in the mute position.
• Verified that the ringer volume was turned up.
• Force restarted the phone.
• Reset All Settings
• Reset Network Settings
• Settings > Phone > Silence Unknown Callers > Off
• Settings > Phone > Blocked Contacts > Verified that this individual is not being blocked.
• Settings > Messages > Blocked Contacts > Verified that this individual is not being blocked.
• Contacts > This Individual > Text Tone > Note <= Also tried other tones
• Verified with the sender that they are not blocking me.

Any thoughts on what may be going on or did I just miss something simple in the configuration?