I was working on my submission page for Lone Rabbit's Pastime jam, and I left the tab open because it was taking a long time to complete. Of course it wouldn't save my work.
I actually think I closed the tab and didn't even get an "unsaved work" warning. Was reluctant to push the the "submit" button because it's kind of unclear if changes can be made later.
I never hosted a jam, but why would it not be possible to make changes later?! That makes no sense. Adding a warning about unsaved changes is a good feature to request though.