TCX exported elevation: lots of NaNs?

Hi,

I just started using this site to plan routes with custom waypoints. The functionality and ease of use is mind blowing. I was able to create a route within a couple minutes, and also add custom waypoints to the cue sheet, and the exported cue sheet is read by my Wahoo unit, which is not accessible in any other free route planners. Massive Kudos!

However, I noticed that the exported .tcx file has lots of NaN entries in the exported elevation field, which confuses my Wahoo headunit. The headunit reports that my simple route with ~400m elevation has over 7000m elevation change, and the upcoming elevation plot is full of mini hills every few hundred meters.

Is there a known issue with the elevation calculations? If needed, I can share the route I created and the .tcx file.

Thanks in advance,
 Adam