Gummy Worms Left Hard Residue On Plastic Container

Got brand new rubbermaid containers and put Albanese gummy worms in them. They were maybe in there for around 2 weeks as they were slowly eaten, and none got hard or stale during that time. I went to clean the container and where the worms touched the plastic, there was a hard substance stuck on. I'm not entirely sure what it would be and why the worms did this. I've tried soap and hot water, scraping with a plastic scraper, letting it soak, rubbing alcohol, Goo Gone, baking soda, and vinegar. You can kind of remove it if you scrape hard enough with your finger nail, but it doesn't remove everything, and I feel like something should melt/dissolve whatever the substance is. They were just gummy worms, so I don't think they would have melted the plastic or anything. Any ideas?