I noticed a change following Shadowkeep's release regarding helmets that have either the Tangled Bronze or Descendant Vex Chrome shaders applied to them that causes any lights/glowing parts to not be lit/glow. This might be intended (or might be a problem with only my installation of the game) but I thought I'd bring it up anyway, just in case. The accompanying screenshot showcases the difference between pre-Shadowkeep and post-Shadowkeep.