I’m not actually sure what it’s supposed to return honestly- the docs say it returns a region which doesn’t make sense, because a region doesn’t have anything to do with bmesh types. What it actually returns is a dictionary with a single key called ‘region’ that has an empty list assigned to it:
dict: {'region': []}
Based on how other bmesh.ops calls work, I would expect it to return a dictionary of changed geometry, such as faces, edges, and verts?
I’m on Blender 3.3 currently, is anyone aware of a bug with this bmesh.op that was fixed in a later version?