299 here. My manager told me if they've been at the window for 30 seconds and I'm missing something to yell out for it to make sure someone is either working on it or knows it needs to be made.

From my experience when it comes to communication, making sure your messages are received is just as important as giving those messages in the first place. If you don’t get confirmation from fellow partners that they heard and acknowledge what you’ve said to them, then they probably haven’t. There’s no way to know if that’s on your end or theirs here, but either way, it can’t hurt to follow up with them or address them by name initially to make sure they’re listening. You might have better success that way. “Hey [name], I already started that frap for you, ok?” or “This just needs ice, [name], got it?” And if they don’t acknowledge with a “heard” or “yes thank you” then you should repeat yourself until they do. You can also fuel this improvement by considering the times you have been slammed or stressed because things weren’t going well— maybe nothing was stocked or the shift wasn’t staying focused or you wasted time remaking something that someone else already started. Try your best to not let your coworkers be put into that position. Think about the things that you’d say “man I’d be pissed if we ran out of X and nobody told me!” It never hurts to let people know what you’re doing, what you need/have, ask questions, etc. Hope this helps!