That happened to me too a few weeks ago. My personal account and Prism & Pen were marked as being under investigation.
I was grateful that once people who had direct lines of communication alerted Medium staff, it was taken care of fairly quickly, but that did not undo the damage done by the fact that we had several popular stories promoted on social media at the time, and the people who clicked on promo links were getting that ominous message about us. The idea that we were “under investigation" hurt our reputation.
I understand the challenges in trying to leverage technology to manage platforms, but I think a more human level of engagement needs to take place before publications get disparaged like this.
By the way, we have a Slack channel, and that did help. I’m not sure why Slack channels for publications should have a bad rep. That’s a perfect way for editors to communicate with one another. And I guess we could do a Facebook Messenger group or something. I’m not sure what the problem with Slack is. It functions more adequately for us than Messenger would or something like that.