@Vector-Rock This one can be replicated easily now, and will be fixed.
The composite shape was empty because the result from combining the 3 shapes was an empty shape due to a bug. The bug will be fixed in the next build.
BTW: in this case one of the shapes is not necessary, as it is the boundary of the other two, and the composite shape is also creating a boundary (kind of creating boundary twice).
About the forum images: yes there is some size limit to the images. I will check if this can be increased, but there will be some limit anyway to keep space under control