Hello,
We recently discovered an issue with the Flight Tracker tutorial. The line causing the problem, SplineTrack->ScaleVisualizationWidth = 70.f;, is not necessary for the project and should be removed or commented out.
The tutorial page has been updated to omit this line.
Please see How to deal with these package error? - #3 by yuan1405 for more information. Let me know if you are still experiencing issues with the tutorial!