Hi Leonid.

FYI: this is on UNA 9.01. Haven't upgraded to the beta.

please specify does your Unauthenticated level have the allowed action "View channel"?
Yes. That's what's strange. Posting a hashtag to the homepage timeline should not then prevent guests (unauthenticated) from seeing that entire channel thereafter (guests then see a blank browser page). Something blocks guests from seeing a channel once a hashtag is posted somewhere outside that channel.

"Posts to Channels directly do not appear on the homepage timeline/outline " - correct, because Channels have own visibility and can't be shown in the public content. 

Got it. Thank you.