Okay. So you guys will probably roll your eyes at this one.
I load Basecamp (on a PC because it doesn't want to recognize my Xt on the Mac ).
Connect XT. All working great.
I do not import or export *anything.* Basecamp shows the standard installed Garmin maps. The "internal storage" is empty.
And yet the XT has series of tracks from one of my GPX files. WTF! Can I delete these. No way . I even reset the whole device and spend a hour reconnecting Bluetooth etc etc .
Start it up - and the #$%^ tracks reappear. #$^#&#%#&%
And then it dawned on me. Log onto explore.garmin.com. And there they are. These tracks are quietly being "resynced" wirelessly.
So I delete tracks in Explore. And Presto! All tracks deleted. Happy days.