I decided myself. A person helped with exactly the same problem from another well-known forum of the site. In the settings of the subscription group, there is a “note to the verification” from the bottom, it was necessary to attach a screenshot there. I thought he was optional. And the subscription immediately became "ready for verification".

A week ago from my first request, and I got a approved mail. Guys, who has the same trouble, mention that and just wait.

I am waiting at least for a week

Same( 12th of April submitted for unlisted distribution. No feedback yet. Apple review team said to wait...