I have a SHAPE-dataset with lines that I turn into polygones with the bufferer. Some of the lines are on top of each other, but that was never a problem so far. But now I have a new bunch of lines where for just a few, the bufferer only puts out one of the overlaying buffered areas insead of both. This only happens with about 10 lines while it works fine for the other 300.

So far a could not find a common trait for those where it doesn't work compared where it does work.

The lines are normal lines with no self-intersections (according to the GeometryValidator)

Does anybody have a clue, why this might be happending?

Thank you!