Batch crop and straighten issue

I have a large number of individual images each on a solid background. Here is an example of an image

Now I want to crop and straighten. If I use the "crop and straighten" tool in cc it works 90% of the time but the other 10% it decides that there are two images and not one so it creates a second file. There is only ever one image in the file.

How to manually achieve this with an action? I tried making the cartoon a solid colour as a new layer and then straigthening that layer but I cant seem use crop and Straighten on more than one layer at a time. 

Any clever solutions? I think this guy had a decent idea but I would quite understand

Thanks, James

Crop and straighten Images settings