Possible fix for those still having issues. I was having this issue with my spouse. I tried everything recommended in this thread and in others. I checked her status from my son's iPad and realized the "notifications silenced" message seemed to be specific to me. I did not see the same message when trying to message my spouse from my son's iPad.
Here's what I did:
- Went to messages on my spouse's phone (the phone giving the "notifications silenced" message). I went to our message thread. She had me pinned at the top of her messages. I long pressed my picture and toggled "hide alerts" on and then off again. It was already in the off position, but I toggled it anyway.
- I unpinned our message thread, I swiped our thread to the left while viewing all messages and toggled the alert icon (bell) on and off. Again, it was not on or silences but I toggled it on/off again anyway. This is probably the same as hiding alerts in step one above, but I was trying everything at this point.
After doing this, the "notifications silenced" on my wife's phone went away. I did not restart any devices. I'm not sure exactly how long it took as I stepped away for a few minutes but this did it for me.
Hope this helps.