I am stuck.
I am trying to create a Crowdsourcing Reporter App based on the Crowdsourcing Reporter App Template. I created a layer with the recommended fields and published it. I created a map with this layer, configured pop-ups and editable fields, saved the map and shared the map with my reporter group. I went to the group, created a Web App through the share button, configured the basic settings but when I want to view my app it says "Configured group is invalid or no items have been shared with this group yet." But I did a map and the map is visible in my group! 
Before I was able to create this app but wasn't happy with the settings for editing so I went back to the map. But when I went back to the app I got the same message. So I started again with a new group but that also doesn't seem to help.
Any idea what I'm doing wrong?