I have a rigged character which is animated in Blender and exported into Unity. Blender animation looks fine. Unity animation has "seams"/offsets in the skin of the arms and hands when the animation causes a lot of deformation. I didn't turn up much in searching, except "quality level". I tried Auto/1/2/4 bones, with slight effect, but never really acceptable. Vertex weights have been regenerated, UV maps checked and fixed, nothing seems to help much. Maybe someone has tricks to work around this.
I've never seen that happen before. If you upload the blend file I can take a look at it.
Thanks anyway jgonzalez . I can't really show the .blend.
I made one more desperate attempt and it seems to have gotten better. I just deleted the prefab completely, re-imported it, and began entering all the complex settings all over again. I had avoided this in the past (used "copy/replace in explorer" update method hundreds of times) for many iterations. Shape seems OK for now, my animation is slightly broken.
I'm not sure what settings you're using in Unity when importing. Are you using the latest version of Unity? In previous versions there was a vertex limit and when you went past that on a single piece of mesh it would cut it up for you. Also if you have any kind of modifiers on your character in Blender I would apply them and export.
You could troubleshoot it a bit more to see if it's the rig of your character or just the character in general. Export the character solely as a mesh to see if that's the issue. If you're using a custom rig setup like Rigify or something along those lines it may cause issues in Unity as it wouldn't recognize a lot of it.
Thanks jgonzalez
Actually everything seems to be working fine now (yay) after a clean FBX import from scratch and setting up all the animation parameters and masking again. So I guess internal data had eventually gotten corrupted in Unity. I've done the "copy/replace in explorer" update a few times and issues haven't returned. I guess I'll just keep my eyes open.
I'm using 2017.2 (forced to collaborate in a team). The mesh vertices are less than the limit, although the total Blender tris are > 65,000 (which worried me for a while). I export by selecting the skin mesh(es) and armature, then export "Selected Objects" Empty+Armature+Mesh.
techworker1 Unity 2018 has gotten rid of that limit, I'm not sure if it was removed in 2017 or not. Nonetheless glad you got it working. When all else fails, just re-export and try in a fresh project. It's not ideal, but sometimes Unity is a pain with weird bugs that are resolved when refreshing it.