I just found a small and nasty issue with creating trigger zone that uses "below/above" creation rules.
Small reminder how elevation test work:
If you define to your trigger_zone "elev" element, you should define elevMin and elevMax if you wanted specific volume area and not on ground.
In v2.0 I have added the "below" and "above" options to make it simpler. You just define min elevation and "above/below" rule, and it will create the volume accordingly.
The issue arose from the fact that the "Visual Cue" switched the value between Min and Max if Min was higher the Max, and when we tested elevation, the code skipped elevation tests if Min elevation was equal zero.
So there was a small mess, and I had to clean this issue.
When using "above/below" I added a dedicated code to test elevation that will not fail if minElev was Zero.
Basically, if Max elevation was defined, then we used the max elevation, else use minElev (even if it is Zero).
Once I'll finish do some more tests, I'll publish the fix.