Why we can't create a stacked bar chart?

1. A concise explanation of the problem you're experiencing.
We can't create a stacked bar chart. The bars are missplaced due to an issue we can't identify.
We created this jsfiddle for you to check the issue https://jsfiddle.net/pleone/xzqzLzpt/

We are creating separate boxes where the first box starts at z=0 with a magnitude of, lets say 10.. then the next box has a z=10 and a magnitude of 20, for instance...

It makes sense that one bar starts when the other finishes, but as you can see in the example, it does not happen that way.

Terrain altitude, height in coordinates instead of meters, I've no idea!

Any idea??

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
I'm trying to display ticket volumes at a certain location and putting a bar aside of the other seems more difficult because we should deal with cartesian radians instead of meters.

4. The Cesium version you're using, your operating system and browser.

Hi Pablo,

It looks like you got an answer from Hannah over on GitHub, but the position is the middle of the box, see an updated example here.