Skeleton don't drop skull

I spawned 7 skeletons and only one dropped a skull. Possibly there is a rare chance a skull will be dropped.

no qmagnet, that's a bug, all of them should drop, for some reason it will always drop 1, how many skeletons you have doesn't matter

Also when you have skeletons, creepers and zombies only one skeleton, creeper OR zombie skull drops

That's MC-63534

Cannot confirm.
Tried that twice and always got a skull, see screenshots.

I did exactly the same like the screenshots and still no skull