I keep seeing this appear over and over again: an older file gets opened (as in a year old, not a decade) on a different computer, and random features have had their direction reversed on rebuild, breaking the entire model.
Things I've seen:
Surface extrudes in the opposite direction
Surface Trim swapping which surface has been trimmed
My personal favorite: multiple sketches with converted entities and drawn entities that have been completely mirrored across the Right Plane.
Sometimes I can get away with freezing the feature tree, but it's definitely not idea.
Is there any way to stop this from happening to me?