Debugging
A setup that works for getting some more insight into what happens behind the scenes is the Stream plugin which gives you something like a timeline of actions on the blog.
Additionally, install the Friends Debugger, it comes with a Stream connector so that incoming and outgoing ActivityPub requests will appear.
As long as the Pull Request is not merged, I recommend using my slightly adapted version that can display the metadata.
Note: Since outgoing ActivityPub requests use the cron system, you need to enable "WP Cron Tracking."
