Though BaseCamp does not seem to be the desired system to work with the Edge, I am quite happy with it, having used it with my Etrex Legend which is still going strong.
Anyhow, on using SendTo... if I select the Edge 800, the GPX file I send gets put in Garmin\NewFiles and all is well. If I select MemoryCard the GPX file gets put in the Garmin\GPX and the track is not picked up.
I work around this problem by using Export (where the GPX will pop up as a Course with SD in front of the name), but it would be nice if the SendTo location could be tidied up as it might explain why lots of people grumble about things not working.
Problem exists on BaseCamp 4.2.2