I followed the instructions in this blog post to create a Lightning component using force:createrecord -
http://www.infallibletechie.com/2017/11/forcecreaterecord-example-in-salesforce.html
I was able to get this to work perfectly fine. I then created a Lightning app which wrapped the component:
In Dev Console, I then clciked on Preview, and it brought up the button in the component. But when I clicked the button, the call to force:createRecord failed. Why is this happening?