A bit of an update. In experimenting more with the 3DR, the transfer is much more reliable than the Skydroid. It works successfully about 3 out of 4 times. The Skydroid never gets past 200 or so waypoints before failing. I am uploading a mission of 419 waypoints.
I cannot see a way to get to settings on the Skydroid. I will ask on the post related to the Skydroid M12L system to see if others are having the issue.
An example of a large waypoint file that always fails with the Skydroid: Shop Back Yard N,W,Sfixmow.zip (4.6 KB)
If you have any insights, though, please help! Thanks so much.