Steps to reproduce

1. Go to travel demo https://demoauthor.magnolia-cms.com/
2. Go to Segments app
3. Select the only folder 
4. Try to click on the 'Publish Inc. Subnodes' action.

Expected results

You should be able to click the 'Publish Incl. Subnodes' button.

Actual results

The action is not available so you cannot click it.

Workaround

Overwrite the action availability rule to allow the action to be clickable.

Adding an empty subfolder within the folder makes the action clickable as well.

Development notes

The personas app does not seem to have this problem. When you compare their definition files, you can see that the personas app does not have the same availability rule that the segmentation app has. 
You can compare lines 128 of personas app definition with lines after 143 in segmentation app definition.

The other alternative would be to specify the node types in the rule for the segmentation app since it uses jcrHasChildrenRule.

6.2 affected, it works in 5.7.10.