Just tested around and found something interesting.
In my drag and drop script that is mainly a copy of yours i found the following line:
if (UICamera.currentTouchID == -1)
On my mac currentTouchID == -1
On my IPad currentTouchID == 0
So that does not work on mobile.
is there any specific reason why currentTouchID should be -1 ?
I just overwrote the line with
and its works now.
The only thing I am not sure if its a bug or misbehaving because of my fix, but the drag movement is very smoothed out / delayed. (cant tell if its writhe that way because i did never seen any drag movement on mobile before.)