External Rel="nofollow"s

rel="nofollow" doen's work for me.
My configuration
Relnofollow ALL External URLs (Yes)
External domains "Whitelist" (is empty)

Please take a look on this post

Thanks for reporting!

/* NOTE: This issue has been resolved. */
The fix will be distributed in the next build.

As a workaround for the moment, you can enter any non-existing domain to white list so that it becomes non-empty.