Hey guys, I have some good news and some bad news. The bad, still no acknowledgement from ArenaNet that this bug exists . . . BUT . . . the good news is that, totally by accident, I discovered a really easy way to kill the Mordrem Predator.
https://youtu.be/2K-fLeIlANA
I hope this helps some or all of you get past this blockage, and thanks to everyone for supporting the reporting of this bug in this thread even though ArenaNet, after a month and many players posting confirmation of the bug, either didnt bother to read them, or, if they did, didnt bother to post an acknowledgement that the bug exists, and what they planned to do about it, on this thread.
Currently AFK auto attacking my way past this while I write this post. THANK YOU for this.