I'll add my voice to the chorus...I'm seeing the same issue.
I first noticed the problem with an old route that used to work and now does not. I was intrigued so I dissected the KML files coming out of Google Earth and noticed that while the Geocaching upload page may say that a route only has, say, 100 waypoints, in fact the KML file usually has about 10-15 times that number in the <coordinates> meta tag.
So seemingly, GC.com is condensing the KML data somehow--perhaps this mechanism is broken?
Having noticed that, I created some custom paths in Google Earth that were under 100 points and verified that the total points in the KML were actually <100 and that it matched the tally shown in the GC.com preview page. I created 3 slightly different paths for the same route (all <100 points, <150 miles)--one of them loaded correctly, the other two still had the same problem. I could find no discernible difference that would account for the sporadic success. (Also tried loading each one three times, performance was the same on each attempt--i.e. the one that worked worked each time, the others failed the same way each time).
I also can't export a route from GC.com as a GPX or KML.
Anyway, IMHO this is definitely broken, but you may have some limited success by creating hand drawn paths in Google Earth and trying to upload those, instead of relying on the routes that are generated by the directions finder. I used the auto-generated route to guide my drawing of a custom path--it's a bit tedious, especially for a lengthy route, but it has better odds of working.
