Put the summary of the bug you're having here

NEW EDIT   replicate by (first of all, my render distance is 8)      do /time set night, wait for mobs to spawn, do /time set day, then tp very high up, or set your spawn on a platform really high up, and do the /tp or /kill, then when you go down, there should be at least 1 mob ghost. that's how I did it at least.

What I expected to happen was...:
The mob to be there

What actually happened was...:
It was a "ghost mob"

Steps to Reproduce:
1. Not exactly sure, but I will type what I think happened.
2. All I know, is that mob ghosts appeared everywhere.
3. I did see a mob die, then a "mob ghost" appear though

Another thing I would like to note, is that they go away after you save and quit.

after original post: I found out that I think the mob has to be loaded during night but during day since they die, they die, but if they are unloaded during day, I think that forms the ghost, for example, if it is night, and you load a mob, but then go up to around build limit, because of the height it should unload them but keep them loaded at the same time, so they die to the burning of day, but don't at the same time. I can't explain the creepers though.