i didnt read all the responses here but it looks like it drifted away from what I believe is very clear and obvious problem: the normal map is bizarre. Thats why it appears normal from one angle but not others.
So don’t mess with any of the microsurface/reflectivity properties until you get the normal map fixed.
Why and how did the normal map get that way? That is a question of how it was produced. That may be involving some other software so it may be best to ask at dedicated forums for that software, or a 3d artist centric forum like polycount.