This is bloody crazy, I've spent the best part of 2 days trying to sort this out and it's still ropey.
"Works in chrome but not in IE, no, wait a minute, I have it working in IE now but not in Firefox, no, wait, it's not working in chrome now, it goes straight to an empty cart, hold on, it is working in chrome but not in safari, wait, it's back in, no, it's gone again......and on......and on........"
I mean the whole system falls down at the very point of
"main" contact with the user, the "ADD TO CART" button!!!!!
Of what use is the rest of the component without this?

!!!!
Any worthwhile, solid solution yet?

??