So I looked into it and it seems this bug was apparently fixed but has returned, I discovered it while messing around with creepers and channeling

I expected to be able to get multiple mob heads when blowing up charged creepers

What actually happened was only one would drop even with enough creepers in the 4x4 space i placed them in to create substantial lag

I simply charged a creeper with the channeling enchantment on my trident during a thunderstorm then ignited it with flint and steel after spawning a metric ton of regular creepers in the same pen. I did this in creative mode so I'm not sure if that was the issue as I haven't tried it in survival but i expect the result would be the same