Weird shading errors on modular meshes


I’ve created a couple of modular meshes to test some stuff inside the engine. They are all based on the same basemodel (the basemodel has been bent for example) and all share the same material / textures:


However, when I combine those meshes inside the editor they have some weird shading:


The scene has a Directional Light and a Sky Light. Lighting only looks absolutely flat and as it should be, so I assume it’s because of the reflections. The Material is a really basic setup, just AO and Normalmap as TextureSample. I assume this happens because when I put them together in the scene they are not handled as a “single” mesh but rather calculate all their reflections split up from each other.

Is there any way I can fix that while NOT combining the meshes? Or is this “error” not an error but just how the engine calculates the reflections?

Just to be sure, here’s the Normalmap and the UV Layout:


Thanks in advance!

[EDIT I] Seems like my Normalmap is the problem. If I put it on my Meshes as Diffuse in Unlit I can see the following:


Where does that come from? I’m using xNormal to render my Maps and the basemodels are REALLY simple. I don’t understand…