The exiled card returns to the battlefield immediately after Isolation Zone leaves the battlefield. Nothing happens between the two events, including state-based actions.

Auras attached to the exiled creature or enchantment will be put into their owners’ graveyards. Any Equipment will become unattached and remain on the battlefield. Any counters on the exiled permanent will cease to exist.

If Isolation Zone leaves the battlefield before its triggered ability resolves, the target creature or enchantment won’t be exiled.

If a token is exiled, it ceases to exist. It won’t be returned to the battlefield.

In a multiplayer game, if Isolation Zone’s owner leaves the game, the exiled card will return to the battlefield. Because the one-shot effect that returns the card isn’t an ability that goes on the stack, it won’t cease to exist along with the leaving player’s spells and abilities on the stack.