Thanks! I've checked and they will display proper framerates once we switch movie metadata to MediaInfo.
I'm not sure why the Windows Media API is returning the wrong framerate, but I suspect File Explorer has a check for invalid values returned by the API that makes it blank the field instead of displaying the value.
My guess is that the cut file has some fields in it which haven't been updated to reflect the shorter length, or maybe a header or metadata that's missing entirely, causing the Windows Media API to miscalculate things. MediaInfo appears to do the calculation in a more robust way.