[VANILLA] Custom settings not saved properly

Here is an example of class I use :

public class PriestSettings : Settings
{
    [Setting]
    [DefaultValue(true)]
    [Category("Movements")]
    [DisplayName("Follow Mode")]
    [Description("Follow the party Leader. Only working when in party")]
    public bool FollowMode { get; set; }


    [Setting]
    [DefaultValue(80)]
    [Category("Heal")]
    [DisplayName("Lesser Heal Treshold")]
    [Description("Limit of Life under which bot trigger LesserHeal.In percent")]
    public double LesserHealTreshold { get; set; }


    private PriestSettings()
    {
        ConfigWinForm(new System.Drawing.Point(400, 400), "Priest " + Translate.Get("Settings"));
    }

    public static PriestSettings CurrentSetting { get; set; }

    public bool Save()
    {
        try
        {
            return Save(AdviserFilePathAndName("McRo-Priest", ObjectManager.Me.Name + "." + Usefuls.RealmName));
        }
        catch (Exception e)
        {
            Logging.WriteError("PriestSettings > Save(): " + e);
            return false;
        }
    }

    public static bool Load()
    {
        try
        {
            if (File.Exists(AdviserFilePathAndName("McRo-Priest", ObjectManager.Me.Name + "." + Usefuls.RealmName)))
            {
                CurrentSetting =
                    Load<PriestSettings>(AdviserFilePathAndName("McRo-Priest",
                                                                 ObjectManager.Me.Name + "." + Usefuls.RealmName));
                return true;
            }
            CurrentSetting = new PriestSettings();
        }
        catch (Exception e)
        {
            Logging.WriteError("PriestSettings > Load(): " + e);
        }
        return false;
    }
}

When trying to change a value, in the resulting XML: 

• the value changed is never saved. If it existed in the file it is totaly deleted
• the value non targeted by the change may be delete also (randomly)