They deleted all private messages on the 4th of this month. It's in response to the GDPR. I believe it simplifies Scirra's compliance by having all communication between users as public.
There was a post by Tom about it a few weeks ago. Also he mentioned it again in one of the website issues topics. I'm having no luck finding it though, there is no search on the new forum, and a google search didn't yield anything on the new site, so ehh.