Despite using the recommended amount of dishwashing liquid and “shine” additive, plus using a dishwasher cleaner religiously, there’s a weird, white film that gets on my plasticware and doesn’t come off until you re-wash them by hand.
Agree, it sounds like chalk - do you have hard water? If so check your salt level, even if you use detergent that claims to have built-in salt action.
BTW, I’ve pretty much given up putting plastic items in the dishwasher. They never seem to get cleaned properly, I think because the surface is so hydrophobic that the water can’t wet them to clean properly. Metal and china comes out clean and dry, but plastic rarely gets totally clean, and even if it does, it doesn’t dry properly.
The same thing happens to my plastic bowls. The weird thing is, the white spots look just like chalk, and seem to scrape off like chalk, but they also seem to grow larger over time, like mold growing. It’s bizarre.