I can't tell if I'm fighting with a bug or user error

Sand Castle Example
The first time you load that example, everything will seem to behave normally. Any subsequent time you press Run (F8) or reload it, the viewer will zoom all the way in as far as it possibly can.

I don’t know if I’m doing something wrong with the CZML or the way I’m loading it, or if I’ve stumbled upon a bug. The issue is present in both 1.75 and 1.76 Perhaps I just need a second set of eyes to catch what I’m doing wrong.

Edit: I should probably mention that any Cesium.HeadingPitchRange setting gets ignored.

If you comment out the last line:

viewer.zoomTo(receiversDataSource);

It will not zoom in all the way. What’s happening is that the first time you open the Sandcastle example, the datasources has not been fully loaded (Cesium asynchronously loads the data sources) when the line above is being called and therefore, the camera stays in the default position.

Afterwards when you press Run, the camera zooms to the receiversDataSource which looks like it’s close to the ground since CLAMP_TO_GROUND is being used.