It seems that a new user can see everything apart from old comments; new comments are fine.
Timeline shows the comments, just the comments tab and widget are empty.
I can see that in the past, there were some fixes related to comments permission propagation? Is it possible that this is a bug again for larger databases? Only new users are affected. I tried creating several, even admins and is the same.
I found a workaround by setting up Module Access Permissions based on groups, but I believe this should happen automatically.