Exporting from Zbrush to Maya: broken UVs


My problem starts with a group of identical low poly meshes in a Zbrush project (3 identical cylinders, 1 subtool, 1 polygroup, no subdivisions). So:

  1. I export them to Maya (export options: merge uv cords checked, export subgroups unchecked, smooth normals unchecked.)
  2. I extract each of the three identical cylinders (Extract faces).
  3. For cylinder #1: I create a planar UV projection and unfold it. UV works fine.
  4. I transfer the UV from cylinder #1 to cylinder #2 (using Transfer Attributes, vertex off, UV sets: all, sample space: components).
  5. The UV on cylinder #2 looks the same but all the UV faces are unsewn.

What to do? If I try to select them and sew them, the UV gets messed up. I have tried reverting normals and different export options.

If I try to create similar objects from scratch in Zbrush (I initialized 2 cubes) and go through the process described, it works perfectly. So I am guessing something in my Zbrush project is not set right. All the other subtools from my project have the same issue.

I don’t know if it’s related, but I noticed that if I assign each cylinder a different polygroup and I export them as an OBJ using the Grp option (one different mesh per polygroup), they get exported as randomly grouped faces (instead of 3 separate whole cylinders).

I have uploaded the subtool here: https://www.dropbox.com/s/gl1ycgh24gfyg7b/cylinders.ZTL?dl=0
I have uploaded the exported obj here: https://www.dropbox.com/s/a7614wjjg7bdeiy/cylinders.obj?dl=0

Thanks for your help!!