How can I view OSMAnd GPX tracks in Mapsource?

MapSource can be a bit fussy about what GPX files it will read. If the GPX file is not valid for some reason, it will usually just refuse to import it (with an unhelpful error message).

One way around this is to process the GPX file with GPS Babel. Just set the input and output formats to GPX, and tick the box to process tracks. This usually produces a GPX file that MapSource can open.

It could be worth checking if you GPX file is valid, or what is wrong with it. See the instructions here: Validating GPX files. Or upload your GPX file somewhere, and I will check it. If OsmAnd is not producing valid GPX files, it could be worth reporting it, to see if it can be fixed. I found a previous report (and suggested fix) here Issue 431 - osmand, though I'm not sure if it has been implemented. Worth making sure you are using the latest version of OsmAnd, to check if it is fixed.

You can take the gpx files and upload them to OpenStreetMap. There you can use them for reference when editing.

As for Mapsource, this forum is about OpenStreetMap specific issues, so your best bet is to go to a Garmin forum. There's lots of documentation on the OSM wiki about using Garmin devices and software with OpenStreetMap.

I have found that I can upload the OsmAnd gpx file to GPX Trackmaker, which is free to download and use. It will convert the file to xxx.gtm. Save this as a GPX exchange file. You can now open it in BaseCamp. Mapsource is an old app.

I sometime use Garmin Basecamp, but i think this program is simpler to use and OSM map background displays as well so try GPX Track Editor, see http://www.gpstrackeditor.com/ it's also on google play i think, so android as well as Windows, and it's free on windows.