"No training data found. 0 invalid files found." when training a set of images into Core ML

I am attempting to load a set of images into Create ML so that I can train an image classifier model. However, when I select the folder that my training data is in, I get the error "No training data found. 0 invalid files found."

My data is laid out as such.

Code Block 
Parent folder
	-Training data (Selected in Create ML)
				-Individuals for each class
						-Image files
	-Test data
		-Individuals for each class
						-Image files

My dataset can be viewed here