Cant delete trees in editor

Hello everyone,

I’m currently recreating my hometown airport, Weinheim (EDGZ). I’m getting along quite well with the editor so far and have already built a bit.

Unfortunately, I’m having an issue removing trees .

As you can see in the screenshots, many of the trees cannot be deleted. Because of this, I can’t continue working on the project.

So far, I have tried the following:

  • only an exclusion rectangle
  • only a polygon
  • a polygon and an exclusion rectangle
  • a polygon defined as an apron
  • an exclusion rectangle with the polygons disabled

What am I doing wrong?

I built a simpler version of this airport for FS2020 some years ago, and everything worked without any problems there (Don’t have the files anymore).

Does anyone have an idea?