[HOW-TO] Getting started with the SDK / Dev Mode

Hello everyone.
Thank you for your great job.
Previously I used Sketch-Up & WED on X-plane. Now, I would like to import, in MSFS, the objects (buildings, churches, etc.) I designed for X-Plane and … I’m quite lost.

For learning, I started whith the included samples, trying to place - somewhere in the world - the object box included in the simple scenery.
So, 1st step (build package) is OK (even with many errors, but it should be ok).
Then, I close and restart the simulator.
2nd step: load in editor “my scene.bgl” and … see the following picture:

The same if I select the location, in decimal degrees (it works) and, then, enable the developer camera (still without opening the project). See the following picture:

In both case, the plane moves into an hangar whith a flikering floor!!!
The sole recovery is go back home (the main menù).

Where am I doing wrong?

Thanks in advance for your support