So you're claiming that at the moment you unlocked level 28, you were left with zero blueprints in all 9 slots????? Now that, my friend, is a statistical impossibility. Okay, not impossible, but so improbable as to leave no meaningful difference between the actual probability and zero probability. No one is going to believe that you received exactly 19 of each individual blueprint up to that point. (And if you really did end up with zero in each slot, it tells me that you've been buying blueprints with Diamonds up to this point. Which would explain you being surprised at this situation when you are in such an advanced era.)