You will probably not be able to get a real 0 distance gap. If it's a face-to-face 0 distance, the software is going to want to eliminate the common face, to make a manifold body. If the situation creates an edge-to-edge 0 distance, that's the dreaded 0 thickness condition (search the community for "zero thickness").
The best you'll probably be able to do is some number smaller than your tolerance, like 0.0001 gap. It's just a mathematical/CAD limitation that we tend to hear about every few months.
I get the following error (google translate):
Selected folded not form a valid two folded corner. Folded must share a common face and bending angles must be over 90 degrees.
On the attached files, the program doesn't let to apply a close corner feature over the file 1, however works fine over the file #2 if I previously 'clean' the peak of the corner.
@schako, there's a problem when you flatten out the interior Flange22 and Flange23, they will overlap. Are you really trying to create a punched/drawn feature rather than bends?