Error Message won't let me log in!

Hi everyone,

Keep getting this error message everytime I try to start something new in Sims Studio. 
Anyone got any ideas what I should do?
Thanks


Sims 4 Studio 1.0.0.1 (Appleseed)
System.ArgumentNullException: Value cannot be null.
Parameter name: source
at System.Linq.Enumerable.Cast[TResult] (System.Collections.IEnumerable source) [0x00020] in /Library/Frameworks/Xamarin.Mac.framework/Versions/2.10.0.81/src/mono/mcs/class/referencesource/System.Core/System/Linq/Enumerable.cs:938
at S4S.UI.Core.S4SWindow.ShowCASPicker (S4Studio.CASPickerOptions options) [0x0005b] in /Users/A/Desktop/S4S/TheS4Studio/S4Studio.Mac/UI/Core/S4SWindow.cs:303
at S4SWindowDelegate.ShowCASPicker (S4Studio.CASPickerOptions options) [0x00011] in /Users/A/Desktop/S4S/TheS4Studio/S4Studio.Shared/Common/Common.cs:1241
at S4Studio.Shared.App+<>c__async1.MoveNext () [0x000c4] in /Users/A/Desktop/S4S/TheS4Studio/S4Studio.Shared/ViewModels/Core/App.cs:488
--- End of stack trace from previous location where exception was thrown ---
at (wrapper managed-to-native) AppKit.NSApplication:NSApplicationMain (int,string[])
at AppKit.NSApplication.Main (System.String[] args) [0x00041] in /Users/builder/data/lanes/3508/eef1c7a7/source/xamarin-macios/src/AppKit/NSApplication.cs:94
at S4S.MainClass.Main (System.String[] args) [0x00007] in /Users/A/Desktop/S4S/TheS4Studio/S4Studio.Mac/Main.cs:13