So, there are many bugs surrounding Vay Hek, and they have been around for a really long while.
These bugs include him not dropping items when killed, no pigments and etc. and the worst of all not even spawning at the last phase of the mission. I've seen forum posts about this from more then 3 years ago, and none of those bugs have been fixed. The drops and spawns must be fixed, and I'm not even talking about the bpring fight itself. I am allways pissed when the sortie assassination involves him. DE FIX PLZ