Mudbox :: Seam Artifacts With Baking Displacement Maps?

We're experiencing some artefacts near UV seams on our baked displacement maps. We have a clean, multiple UV-tile model which is subdivided, sculpted etc. Baking uses subdivision method, smooth target mesh and UVs on (we render with prman). Edge bleed is default 2, anti aliasing to x2.

Then test the map out by bringing the target model back in, subdivide up to the corresponding level, and sculpt using maps. The artefacts are not everywhere, just on some UV boundaries in some areas, very strange. The UV boundaries are clean quads, same spacing, good use of UV space. My concern is its in sporadic regions, and not globally over all seams.