Normal map compression error?

So basically I have created this window in Substance painter and the display in substance has this nice subtle normal map definition:

However when I import it into unreal the combination of the normal map and the roughness/metallic seems to be creating these weird split effects.

Originally my first thought was that it is to do with compression however I have tried the following and nothing seemed to work:
-changing the compression settings for the images in unreal
-changing the bitrate in substance/photoshop
-using srbg or rgb
-definitely seems like the metallic is what makes the definitions obvious even if the normal map is what creates the effect
-for some reason the other metal objects dont show signs of this, so I tested to see if there needed to be more depth, this also didnt have the desired effect
-tried separating the actual window part of the mesh so the face normals could maybe look better

Whilst I would probably be able to resolve this by making the window completely flat, it’s not the look I was going for and would like to know for future reference, so if anyone has any ideas for a fix, please let me know.