Why do waypoints from an imported gpx file route not show in My Collection

Well that's no doubt due to the gpx file, where are you getting it from? How do you know it includes waypoints?

The gpx file came from a motorbike magazine website. When imported, the route shows correctly in Basecamp and I can get a list of the waypoints with 'Get Info' on the route. From what I can see, if I create a route by manually creating waypoints they are listed in the list folder and are again listed when listing everything in the top level of My Collection. However an imported route does not have any listed waypoints in the folder.

Am I correct in assuming that any waypoints listed in My Collection can be re-used in a new route? Is this how it works?

Garmin has always done "creative" things with its XML coding, found in GPX files. The answer to your question may be that the bike mag uses one way of coding the waypoints and Basecamp expects to see another. You can test this by exporting a route from BC whose waypoints show up in your collection and compare how they are coded to how the bike mag file is done (they are plain text files).

Thanks for the reply.

The imported gpx file from the bike mag shows waypoints as below:

<wpt lat="52.97894" lon="-0.026577">
  <name>Boston</name>
</wpt>
<wpt lat="53.6142051" lon="0.1401227">
  <name>Spurn National Nature Reserve</name>
</wpt>

Manually creating waypoints in Basecamp and saving the gpx file shows:

<wpt lat="53.659588498994708" lon="-0.277369664981961">
    <time>2020-05-24T13:30:00Z</time>
    <name>53.6595885,-0.2773697</name>
    <cmt>Kebec House, Townside, East Halton, Immingham DN40 3NL, UK</cmt>
    <desc>Kebec House, Townside, East Halton, Immingham DN40 3NL, UK</desc>
    <sym>Flag, Blue</sym>
    <type>user</type>
    <extensions>
      <gpxx:WaypointExtension>
        <gpxx:DisplayMode>SymbolAndName</gpxx:DisplayMode>
      </gpxx:WaypointExtension>
      <wptx1:WaypointExtension>
        <wptx1:DisplayMode>SymbolAndName</wptx1:DisplayMode>
      </wptx1:WaypointExtension>
      <ctx:CreationTimeExtension>
        <ctx:CreationTime>2020-05-24T13:30:00Z</ctx:CreationTime>
      </ctx:CreationTimeExtension>
    </extensions>
  </wpt>

So, there is a lot more information in the Basecamp created waypoint.

Garmin support didn't know why the waypoints aren't saved. Quite rightly they said the imported gpx file was beyond their control as to its contents.

It seems that manually creating a waypoint close to the desired location of an imported waypoint is one solution.