Create Route from Track omits elevation

I've downloaded some Routes from the web. They've been created as XML tracks. A typical point looks like this:
[FONT=courier new]<trkpt lat="46.554380021989346" lon="11.760569969192147">
<ele>1566.5409099999999</ele>
</trkpt>
[/FONT]
NB there's an elevation at every point - very useful.

So I import into BaseCamp - fine.
Then in BaseCamp I create a Route from the Track - that works
BUT the elevation is omitted from each point in the newly created Route !!!

[FONT=courier new]<rtept lat="46.554380021989346" lon="11.760569969192147">
<time>2018-04-11T19:27:15Z</time>
<name>Mountainbiken durch die &amp;quot;Steinerne Stadt&amp;quot; am Sellajoch</name>
<cmt>Mountainbiken durch die &amp;quot;Steinerne Stadt&amp;quot; am Sellajoch</cmt>
<desc>Mountainbiken durch die &amp;quot;Steinerne Stadt&amp;quot; am Sellajoch</desc>
<sym>Waypoint</sym>
<extensions>
<trp:ViaPoint>
<trp:CalculationMode>Direct</trp:CalculationMode>
</trp:ViaPoint>
<gpxx:RoutePointExtension>
<gpxx:Subclass>000000000000FFFFFFFFFFFFFFFFFFFFFFFF</gpxx:Subclass>
</gpxx:RoutePointExtension>
</extensions>
</rtept>
[/FONT]

I can't see anywhere in BaseCamp to alter this behaviour - any advice ?