Since the question was not about any code written while using dnSpy, and pertained to the results produced by dnSpy during normal use, I figured it belonged on SuperUser instead of StackOverflow.
I'd say it's a bit of a gray area. In reading your question, I personally would have left it open on the basis that you were asking about functionality rather than development, but we do (IMHO) have some (too often overly) aggressive closures here.
I do think this is likely on-topic on Stack Overflow. My justification would be that you are asking about:
- software tools commonly used by programmers
- a practical, answerable problem that is unique to software development
That second one might be a slight stretch, but it does seem to me to be a question best answered by a developer. I do see quite a few dnSpy questions on Stack Overflow, and many of them are even more "general functionality" than yours.
My recommendation would be to repost on Stack Overflow. If for some reason it's closed as off-topic (which I really, really doubt), then that would be a case for having it reopened here.