Entities disappear if they have items that the player gives them.

I had a zombie and I caught him and then gave him armor and sword but when he returned this entity disappeared, the items that I gave him had a name and were given by the player with a dispenser but this should not disappear is a bug. But if it works if you die and a mob takes your things, it persists but if you give it to them with a dispenser it disappears.