Just finished “Buried Insight”, both this and the last mission, I received the mastery point that you would normally get at the end of the instance, I got near the end but not exactly at the end. Same thing happened on the mission before Buried Insight.
I was also with my fiancee and she got hers at the end of the instance which is what I used to get in earlier missions before the latest patch.
So yeah, seems like the instance creator gets theirs a little earlier instead of at the end (though the reward screen still mentions it, you just get it earlier than the reward screen).
Like I said, minor bug but thought it was worth mentioning.