Thought this might help, as I have spent quite some time before figuring this out.
Despite having set all my layers to triplanar in SP, I kept getting a very visible seam when adding normal map to the material.
The solution for me was inverting the green channel of the map. You can easily do that in PS ( https://www.youtube.com/watch?v=cu1Pv56MS_Q )
Cheers.