Hey OneNot, not sure what could cause this issue I’m not very familiar with instanced static meshes. All though I believe any static mesh particle system would be using them which this is the ended purpose of the script. Any transforming of the vertices is happening via world position offset so it definitely should be taking into account any prior transforms. It’s also strange that it’s only certain vertices or at least skewed. From what I can tell by the image anyway. The offset image just tells each vertex how far they should move from their original position each frame. Each vertex would just have a new initial transform after you’ve rotated them it shouldn’t matter.