Omg I thought lid wasn't really necessary since customer's picture is without it oops my bad. But right now I'm replaying and seems I got new bug where I can't place cup on white place, at least on 2 web browsers (Firefox and Chrome) so I'm not sure what's causing that. Download version seems to work better?
Answering your question, putting milk,ice cubes and straw into cup worked but liquid with ladle seemed to be bugged. I tried clicking on a cup with cursor(with selected topping before) and above it but cup isn't changing. Both web and download version seem to have that problem. I hope it helps you find that bug