Having the material from your library feature profiles transfer to your structural members is a new feature released in SW 2016, and seems like a big win for driving material callouts down stream. I've recently discovered that there at least two things that can break these links, namely Trim/Extend features between structural member features, and Cut Extrudes or Hole features added to any of the structural member features.
In both cases, the profile material now becomes linked to the document level material instead of being applied at the body level for that/those members, and the previously linked body level material no longer updates when the profile is changed for any reason in the future.
Would anyone care to replicate this behavior? It'd be nice if this turned out to not actually be a bug