UE5 Texture problem: RGB Flakes in black Albedo PBR

Hi, im working on a virtual production set and am of course trying out UE5 for the project (i know, it is early, not production ready)

This problem occurs from time to time:
PBR Workflow:

100% Black Base texture RGB. Tried also png/tga format with 8bit, 8bit dithered and 16bit and 16bit dithered. Just to be thorough.

I get these artifacts on the albedo. No idea where it comes from.
Does anyone has an idea?