Only anecdotal for now (I will be keeping track of armour drops and make edits to this post with numbers to corroborate), but over the past few days I've been attempting some armour farming and the vast majority of armour drops that roll as powerhouse include health as the 3rd stat (I'd say around 66% to be conservative, feels more like 75%), including armour from Master raids. Other focusing mods (skirmisher, gunner, paragon, etc) seem to drop with more consistently spread out stat rolls, but for some reason powerhouse (at least in my recent experience) tends to drop with health as its tertiary stat (as a hunter this is quite annoying but no so bad on warlock). That said, there are some armour drops which do not drop with health, but they are far less frequent than the ones that do. I'm not sure if this is just god-awful RNG or if anyone else has experienced this same pattern. This same issue happened to a clan mate of mine yesterday during Master VoG, where nearly every piece of armour that dropped for him had a tertiary health stat despite not focusing for it. If this has happened to you I'd love to hear about it so at least I know I'm not going crazy, and maybe we can get some attention on this before the final patch update!