Why does "Mark Unread" cause Smart Rule to Fail?

Consider the Smart Rule and script below which indexes the content of a bookmark.

If I remove the step “Mark as Unread” it works fine. If I add that step back in, the script does not work. Why?

The “Execute Script” action can be only performed asynchronously in the background if it’s the last action. Otherwise, like in this case, it’s performed immediately but downloads are always asynchronous. The next release will fix this but I would definitely recommend to change the order of the actions.

That works! Much appreciated