It’s now been more than 10 hours of gameplay and no Primal has dropped.
After spending over 150G, 50 visions, and thousands of crystals at Kadala’s.
According to your figures, we’re looking at 1 Primal per 400 items, so I must be at over 2,000 without a single Primal. Is this normal?
I should point out that I have unlocked the quest and completed the ALTAR.
It’s a rate, calculating on thousands and thousands of drops, it’s not a truth.
So keep farming/gambling, and good luck.
Bad luck is still not a bug!
On a humorous note, I’ve never seen anyone write on the Bug Report because they got a double drop of primals.
I can confirm that primals do drop from visions in the EU region (got some today 
). But at other times one can run the same amount of visions/greater rifts and not get any.
When farming visions one usually just leave and start games. But if you feel that the drops are off - like only getting visions that are few levels low and the rift guardian trios hardly drop any keystones - it could be an idea to exit Diablo and start the game from battlenet all over to maybe get a “better” server. And it sometimes works! This is likely just superstition but at least you feel that you have tried to do something to improve matters!