https://codepen.io/spiderwebdesign/pen/abXjWJz
Thanks for the Pen idea. I found the problem. I removed 'bounds: container' and now everything works fine. The problem was only occurring in Firefox mobile.
The dialog window was offset from the center. It had the LEFT side of the dialog in the center of the screen instead of the center of the dialog in the center of the screen. Just removed the bounds and it's mint now.
Draggable.create(dialogWrapper, { bounds: '.container', trigger: handle, transformOrigin: "50% 50%" });