UIStackViewBug.swift

import UIKit
import PlaygroundSupport

let stackView = UIStackView.init(
    frame: .init(
        x: 0, y: 0,
        width: 100, height: 100
    )
)
PlaygroundPage.current.liveView = stackView

let subview = UIView()
subview.backgroundColor = .red
stackView.addArrangedSubview(subview)

UIView.animate(withDuration: 1.0, animations: {
    subview.isHidden = true
    subview.isHidden = true
    subview.isHidden = false
})