bsdtar gives (Empty error message) when trying to extract an ISO
This isn't a great solution, but it's possible that the bsdtar shipped with High Sierra is buggy (if I get time, I'll bisect the libarchive repo to see where this occurred).

A workaround is to install the latest with homebrew:

brew install libarchive


This formula is keg only, though so you'll need to add $(brew --prefix libarchive)/bin to your PATH to be able to invoke with just bsdtar.