send email to revision author but not to node author does not work

Sending emails to the revision author (neither current nor latest pending draft´s) doesn´t work via rules.

• the tokens [revision:author:mail] and [node:author] both go to the node author.
• the token [revision:revision-author:mail] works via actions but shows "array" as a result via rules (also stated here: https://www.drupal.org/node/2296419)

Can someone help?

Thanks