The browser response headers shows the content-disposition header, but when console logging the response headers it appears to be missing.
The expected behavior using 'Content-Disposition' "attachment" type is that the browser save dialog appears, but it does not. (at least not in Chrome at time of writing this..)
Please inform us about adding the 'Access-Control-Expose-Headers': 'Content-Disposition' header in the docs for StreamableFile.