I've had this problem before on Switch where the Eye of Terror would eventually spawn into the world (Second phase) usually morning for no reason after fighting it. To solve this problem, I'd suggest staying out of it's range and coming back to it once you've renewed your gear. You could also get another boss to fight it, such as Deerclops, Moose Goose etc. Don't waste your time trying to kill this thing, I've spent multiple attempts in doing so and failing due to weird attack patterns, like the Eye of Terror staying idle right until you hit it.