Hi,
I tried that. First I installed version 4.0.2, but that didn't help.
Then I tested the project and import settings you recommended. Unfortunately, the Bptc Ldr
import setting is no longer available in the current version. Rendering>Texture setting Import Bptc
did not bring any improvement.
I have also compiled the current Master Branch with commit a7276f1ce0c2911216a2c4718efddab98ddffd8f, but still here, the same.
To me it seems to be a bug because this problem didn't exist with 3.5.1. But it could also be a new attitude that I don't know
btw, the normalmap test-image i found here: https://en.wikipedia.org/wiki/Normal_mapping, while the diffuse picture is just a white png with the same size of 4096 x 4096 pixels.
Maybe someone else can reproduce and confirm that issue?