I guess, you are probably talking about ExamplesFileTransfer.WPF?
This is the one I am using right now.
It has this code

 //Limit send chunk size to 500MB
                        long maxChunkSizeBytes = 500L*1024L*1024L;
                        if (sendChunkSizeBytes > maxChunkSizeBytes) sendChunkSizeBytes = maxChunkSizeBytes;

And it is WPF only, so you can’t test it on any other platforms, that is why it has never been tested on Mac/Linux. I guess.