Most layers missing when playing tour

[astrofrog]

When I load the following tour into the Windows WWT client:

https://www.dropbox.com/s/tndimbi8j51hk66/exoplanets_tour.wtt?dl=1

I see seven data layers correctly:

If I edit the tour and set the start and end camera position then play the tour, all but one of the layers disappear (only a few red points remain), and even when I go back to editing the tour, the layers do not re-appear:

If it's hard to see in the GIF above, here's a better video:

https://www.dropbox.com/s/rfm6z4tz5hqgvuw/2019-09-20%2010-25-29.mkv?dl=0

@astrojonathan - do you have any idea what is going on, and do you have any suggestions for working around these issues in the short term? (I originally thought it might be because several layers had the same name, but renaming them did not help)