@KaidoomDev - Thanks for the project.
Your project works with alpha (as does ours), ONLY if no rendering preview is enabled. When setting the rendering preview to any mobile platform and deploying to device, the transparency isn’t there, so, I think there’s there’s probably an issue with the scene depth capture in Unreal.
I did/could not try with the D3D Shader previews - I’m on a Mac, and if I switch to those previews, Unreal crashes 
Android Vulkan/IOS SM3_1:
Preview Rendering Level disabled:
