Repro steps:
1. open project "New Unity Project.zip";
2. build to WSA platform. Build and run generated project;
3. press "save" button, then "load" button.

Exception message:

Exception: One or more errors occurred.
Type: System.IO.IOException
Module: WinRTLegacy
InnerException: One or more errors occurred.
AdditionalInfo:<No Data>
at System.IO.FileStream..ctor(String file, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)

at System.IO.FileStream..ctor(String file, FileMode mode)

at UtilityWinGameLibrary.CXMLFile.LoadGameData[T](String path)

at SceneScript.OnGUI()

at SceneScript.$Invoke0(Int64 instance, Int64* args)

at UnityEngine.Internal.$MethodUtility.InvokeMethod(Int64 instance, Int64* args, IntPtr method)

(Filename: Line: 0)