SettingsPlugin: Unable to store values locally

Hi, I am using v2.5.8 from almost 8 months. It was working fine. Today I tried to update few packages and I noticed that Settings plugin is not working. It is giving following exception.

As you can see my type is int but showing as !0

Below are my objects

private const string PageTypeKey= nameof(PageTypeKey);
private static readonly ePage PageTypeValue= ePage.NotSet;

public static ePage PageType
 {
    get
    {
      return (ePage)AppSettings.GetValueOrDefault(PageTypeKey, PageTypeValue);
    }
   set
   {
    AppSettings.AddOrUpdateValue(PageTypeKey, (int)value);
   }
}

Here PageTypeValue type is int but showing as !0 which is very strange.

I tried to upgrade to v3.1.1(stable) and in this version it is not storing any value. Every time I open it’s (another object which is string ) empty not the one I stored last time.

I will try to make repo as I have more pressing issues in my current project now. Note: I upgraded to vs2017 15.7.1 recently