I’ve got the same issue here and more- bone colors check box doesn’t work and I can’t even get materials aside from the world default to appear on fractured nanite meshes. Also, I can’t select individual pieces while fracturing on a nanite mesh. When I try to select, it is either the whole mesh or nothing. On non-nanite meshes, I was able to select pieces of a fractured mesh, and then perform more fractures on those.
I’m using version 5.4.4