The Blizzard response was that the drops are working just fine but they have a low drop chance. However, I’ve seen posts from people that have opened over 200 bounty caches and still have not obtained the recipe.
Let’s assume that the low drop chance is 5% so…
The chance that a cache will not contain the plan = 0.95
The chance that none of X caches will contain the plan = (0.95)^X
The chance that none of 200 caches will contain the plan = (0.95)^200 = 0.000035
That’s a 35 in 1,000,000 chance. Does that sound like it’s working?