I tend to disagree with Tim's answer that this is a Garmin bug.
I have the same problem as the topicstarter, and I agree with him that it is caused by the airport description with the slashes.
Garmin assumes that a flight goes from one airport to another, and uses/expects the airport identifier (ICAO designator) for all airports which seems to be logical. SD uses identifiers for navaids, why not for airports?
If I save an SD-route as a gpx-file, and I change the airport descriptions in the gpx-file to their identifiers, everythings works just fine!
So, in my opinion, no Garmin bug but a necessary change in SD-software for 'sending a route to connected device' and 'save as gpx (not the airport description, but the airport identifier, that is available and used for the flightplan!).
Tim, look forward for your reaction,
Mark