Operating system:mac os mojave 10.14.5
Graphics card:intel iris 550
Unsubdive either from the edge menu or under the decimate modifier not giving expected result with many production models. This never worked well so I figured I put in a report since I haven't seen an active one.
Exact steps for others to reproduce the error
Attached blend file, unsibdivide fails more often than not, producing triangles with unsubividealbe geometry. Works in other packages though, so it's not a problem with the geo.