Deform objects

You have to look at your UV unwrap. If you use real displacement i.e tessalation and displacement of the height scale and point on the surface will displace perpendicular to the surface at that point. That can cause an issue along UV seams such as a cube, where the texture tile is not mapped continuously across every seam (some are reversed). 

In some software (such as Blender) you can split the operation across several displacements sequentially (using displacement modifiers). This avoids the seams from splitting, as the +/- Y displacement can be applied to the result of the +/- X, then +/- Z can be applied to the result of both of those. Inside Substance Designer you are limited to applying a displacement to all planes at the same time.

Dave