Drop rate of Blueprints

I remember hearing somewhere (pre-launch), that we could expect to do about 1 Grand Heist per Act while leveling.

I just got my first Blueprint (for Grand Heist) to drop, while farming for The Lion in Act 6 (so, time/kills/drops wise, it's more like act 7 or 8).

Did this drop rate get reduced? Or am I just unlucky?

While farming Quarry for Jun I was getting one about every 20-25 instances. Did not get a single one running the actual campaign on 2 characters.

Could be anecdotal but these were my numbers.