The reason it will work with UI culture change in V1 is because the localised characters inside the exception strings have a tendency to cause the richedit view corruption. As soon as the UI culture is set to english, the characters are gone and the problem is gone with them.
NCrunch should be able to support rendering of non-english stack traces. Although I suppose it's possible to force tests to run with a UI culture of en-US, I'm sure this would cause problems for people and there's no guarantee that they couldn't change the culture while the test is running .. so a reliable workaround using this approach doesn't seem to be possible.
Out of interest, does NCrunch V1 try to render links inside the exception stack traces for you when you don't have the en-US culture set? (i.e. when the view is corrupt?).
