When attempting to collect flowers in the wild (possibly player planted as well) the harvested flowers to not drop the flower item.
Linked issues
Comments 3
No, don't lump it with the rendering issues. I tried to pick them up and they flat out don't drop. I was having the clocks not appearing in Item Frame glitch and assumed they were related (as you must have), but in this case they would not pick up, nor render, and therefore, flowers effectively DON'T DROP.
some items are invisible (another bug MC-46081