Hi everyone, I’ve stumbled upon a weird bug/problem on my new project. I’m hoping you can solve it for free! 
An image is worth a thousand words so, take a look:
(if only it was a thousand dollars… 
)
http://i28.photobucket.com/albums/c208/Olivier_Theriault/Polygroups_Problem_01.jpg
i’ve had this happen when i have used edge loops.
the fix was to subdivide with smooth off once, delete lower and reconstruct subd, delete higher then do groups.
however i never use UVs at all or group by UV’s so it may not be related, but worth a try on a cloned model.
run a clean operation on your mesh, before import.
personally never come across any bugs with polygroups.
EDIT: for what its worth, maybe you got some overlapping UVs (it happens to us all sometimes) Maybe try as a test AUV tiles, then group by visible. You’ll know straight away if its UV related.
