Visibile UV seams after baking

hello everyone,

I am using Substance for a while now and never have encountered this issue until now, maybe you can help me to understand what am I doing wrong.

The issue is after importing the model from Blender and baking the meshmaps, the UV seamline will be visible on the 3D model, when adding some bump effect, the line is even more visibile (obviously). 

I made sure there is no UV overlapping, the normals in blender look outside and the UV map has some spacing between elements: 

I find also strange that hese two components don't share the same issue even being the same geometry and close on the UV map (above pic):

here on the rocket launcher

Any suggestion?
Thank you