It's been happening since before the update. No more grandmasters & assassins.
A year or two ago I had noticed that there were two variants of darkling spawns, one of primarily ogres and the other of primarily darklings with ogres mixed in, so I just figured it was a variant of the primarily ogre set.
I couldnt say what affects the spawn at all that'd cause the current situation, maybe there's two halves to the spawn and people would have to kill just the ogres for a while until the darklings have room.
I havent seen any darkling assassins or grandswordmasters in the Mists for a while though either, maybe something has happened to their resrefs or blueprints.
The warriors and lookouts are currently appearing while the chests are at their highest DC locks & value from appearances.