5.1 texture compression bug in shipping build?

Hiya, I’m having an issue with my thumbnails in a shipping build after moving to 5.1 and wondering if anyone could point me in the right direction to solving it?
So it works fine in a dev build and PIE, but when I package a shipping build I get green outlines like in the provided images




recreated it in a clean project, I noticed that the green channel has a white background and if I lower the mip level the green outlines appear. Not sure if it’s relevant since the setting is NoMipMaps anyway.
Seems like it’s ignoring my texturegroup and mipgen settings in a shipping build.

it was a bug in the plugin that I was using, Thumbnailer