If trackpoints are downloaded into TGP 1 set at a time from GH-625XT, and saved in .gpx format, all is OK. If 2 sets of trackpoints are downloaded from GH-625XT at the same time, the first set saves OK as .gpx. When the second (later date/time) set is saved as .gpx, altitudes from the first set appears in the <trkpt records. Before saving, in TGP all information is displayed correctly.
I am using TGP version 1.6.10.