Question StreamBinaryReader fails in build

Entities Version 0.17.0-preview.41
Build Windows Classic Build with IL2CPP

Using StreamBinaryReader and StreamBinaryWriter works fine in editor. However, in build it fails to read, both if I try at start of game, or as a command when running.

I've tested moving my save file between build and editor, and can confirm that StreamBinaryWriter works fine in build, and the saved file opens without problem in the editor.

So is this a bug, or am I doing it wrong?

The reading part of code:

Code (CSharp):

1. if (System.IO.File.Exists(file))
2.                 using (var myReader = new StreamBinaryReader(file))
3.                 {
4.                     var nbOfRecords = myReader.ReadInt();

From Player.Log:

Code (CSharp):

1. Could not open file Jallaballa0.sav for read
2.  
3. IOException: Failed to read from Jallaballa0.sav!
4.   at Unity.Entities.Serialization.StreamBinaryReader.ReadBytes (System.Void* data, System.Int32 bytes) [0x00000] in <00000000000000000000000000000000>:0
5.  

 

when you google your problem, and find your own post...

but then I noticed something strange - how's this supposed to work, haha?

Unity.Entities.Serialization:

public StreamBinaryReader(string filePath, long bufferSize = 65536)

        {

            if (string.IsNullOrEmpty(filePath))

                throw new ArgumentException("The filepath can neither be null nor empty", nameof(filePath));



            #if UNITY_EDITOR

            stream = File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);

            buffer = new byte[bufferSize];

            #else

            bytesRead = 0;

            this.filePath = filePath;

            #endif

        }