Since 2017.2 LayoutGroup restores child properties in OnDisable, to prevent that and force old behavior use this override

GoodHorizontalLayout.cs

//===----------------------------------------------------------------------===//
//
//  vim: ft=cs tw=80
//
//  Date:    10/23/2017 23:10:37
//  Creator: Eugene Mihailenco <mihailencoe@gmail.com>
//
//===----------------------------------------------------------------------===//

using UnityEngine.UI;

namespace BullyFramework
{
    public class GoodHorizontalLayout : HorizontalLayoutGroup
    {


#region Serializable data
#endregion



#region Private fields
#endregion



#region Public methods and properties

        // Copy-pasted original HorizontalLayoutGroup impl, note it calls base
        // OnDisable - i.e UIBehaviour.OnDisable()
        // protected override void OnDisable()
        // {
        //     m_Tracker.Clear();
        //     LayoutRebuilder.MarkLayoutForRebuild(rectTransform);
        //     base.OnDisable();
        // }

        protected override void OnDisable()
        {
            m_Tracker.Clear(false); // key change - do not restore - false
            LayoutRebuilder.MarkLayoutForRebuild(rectTransform);
            // UIBehaviour.OnDisable(); C# sucks on calling grand parent, but luckily in Unity 2017.2 that OnDisable() is empty
        }

#endregion



#region MonoBehaviour methods
#endregion


    }
}