Drag and drop submit button not working on iPad

I have been trying to put together piece of drag and drop content. I have it working fine on desktop (IE, chrome, firefox tested fine) and android phone/tablet but it does not work on an iPad.

Here is a very simple demonstration of the issue. The below link is a responsive project but the problem exists for me with non-responsive too. Basically it functions normally on desktop/android environments. On an iPad however (and possible iPhone too - don't have available to test) the submit button doesn't seem to work. After repeated attempts/long hold it moves on but still doesn't submit.

Does anyone know of any iPad drag and drop issues/fixes - many thanks for any help with this.

http://www.markwaterfield.com/dragTest/index.html