Wanted to report back that the Avatar Warp function now works! Since my last post yesterday, I did two things today: (1) deleted Prepar3D_Default.fxml and let Prepar3D rebuild as suggested by skypilot75 - thanks for sharing the tip, and (2) as I launched P3D, there was a message to update Couatl, and I followed the in-game instructions to update it. I didn't see this in-game message yesterday. Then I loaded KMEM, the Avatar Warp function worked, altough choppy / stuttering as it tried to load the Control Tower, but it worked fine. Problem solved!!