in the past I also had sometimes problems with the gpx import. If you are using BaseCamp you can import that gpx and afterwards export them. So the gpx file is written with another tool and possibly gpx file version. Another good tool is RouteConverter which can translate waypoints and geocaches between different file formats.
If you transfer the complete gpx cache collection with e.g. an Explorer to the GPS file system you can later delete the full collection with one command.