Ian T recently posted a link to a video showing a bug in Freecad:
FreeCAD is Fundamentally Broken
As I have the three packages above installed on my laptop I thought I'd try to replicate what the author of that video did on those packages. Creating the model in those packages was straightforward.
The first one on which I tried to make the change he did was Freecad. My installed version is 0.18 so slightly earlier than his version but yes it failed although in a slightly different way.
The second one I tried was Fusion 360, personal edition. That also failed as after editing the second sketch everything after that sketch disappeared.
The third one was Onshape. Surprise! It worked perfectly.
So it looks as if I will be sticking with Onshape for now. I don't like having my work stored only in the cloud and being made public but as it runs in a browser it works fine on Linux as well as Windows. I gather that a new version of Freecad is due out in December with many bug fixes so I look forward to testing that.
Russell