Could you check out the safari technical preview?
Pretty sure this was a bug in safari proper.
I’m on macOS beta (10.12) so the tech preview should be a good sign of whats coming.
I downloaded the Safari Technical Preview version and it worked Thanks a lot.
This was working for me for a while and then stopped. I think I’ve figured out that the .ts files only appear if you add the --consolelogs flag when running from CLI (even in Safari Technical Preview).