I helped a colleague converting waypoints from a GPX file to a shapefile. My colleague has only ArcMap. I gave him the shapefile and when he opened it in ArcMap, it did not show anything in the attribute table.
I installed QGIS in his machine, we tried with a couple of different GPX files and we have the same problem. The resulting shapefile does not show anything in the attribute table in ArcMap, but we are able to see all the data in QGIS.