invisible items and mobs?

I am making an adventure map i have only made the start but i was testing durability of the armor then accidently died and when i went back to get my stuff i switched to creative mode and the items and slimes disapeared though i could pick up the items and the slimes could attack me, Steps to reproduce: I dont know if it had something to do with it but i was wearing armor from the following command: /replaceitem entity @p slot.armor.chest iron_chestplate 1 0 {ench:[{id:34,lvl:10000}],display:{Name:"Level 2 Armor"}} on a repeat always active command block. so then when i died i had to go into creative fly out of the spawn and get my stuff back but it was gone. please help