Mobs do not drop items when you kill the entity

Are you in creative mode?

I tried it in survival, creative and adventure mode and the result was the same.

Is the gamerule doEntityDrops set to false?

no, i can drop things myself but the mobs do not drop items, all the mobs i check it and wasn't only the armor stands

Actually, is the gamerule doTileDrops set to false?

i resolved it, it was the gamerule DoMobLoot so thank you