STL export Flächen vertauscht in SU Pro 2020

Hallo, when you export STL Files with SU 2020,
Sketchup changes the Surfaces , so one
can not 3D print it, especially if the Objects are mirrored or doubled (in Groups or subgroups). Did you know?

Exactly what does that mean? Can you share a SketchUp model file that shows this?

Are you referring to cases where you have flipped or otherwise mirrored components or groups?

Sorry for my Bad english, I am German.
You make a group, than mirror that group or double it.
Than make a Group over all the subgroups an export
that main group as STL.
So Sketchup changes inside to outside and outside to Josi to inside, one cannot 3D printing it.
Think about a Cabin of a Car with two Fenders, one of Them mirrored, the mirrored is wrong.

Sounds like the STL exporter doesn’t reverse surfaces when the transformation has a negative determinant.

You should be able to quite easily get around this by exploding the groups before exporting.