Unable to block contact on iMessage for Mac OS 10.14.2 I am unable to block a contact on my mac's iMessage app (Mac OS 10.14.2).

I go to preferences > imessage > blocked > + , and then a drop down of my contacts appears. I select the name from the list but then the list just disappears and nothing is added to the blocked list. (And yes they are still able to contact me).

Any ideas as to what I'm doing wrong?
As a workaround, you can add a phone number as blocked in the FaceTime app on macOS, and it will also register as blocked in Messages (at least it worked for me, and I had the same issue on 10.14.3).