When you integrate Status Hero with a private channel in Slack, you'll need to take an extra step within the channel in order to take advantage of all of the features from the bot. Those features include automatic updates to edited check-ins and rolling up check-ins into a single thread.
Essentially you'll be adding the bot as you would another person to the channel, which is an additional security step required by Slack for private channels.
First, visit the private channel and select the "Add an app":
Then, select Status Hero from the list of apps and click the "App" button: