auto-save form progress not working

I have enabled the auto save option. I see whit checkmark in the green field on the left op of the form setting. nevertheless, the forms are not saved. Leaving a page or refreshing the page will result in an empty form.

Whe I revisit thet FormCraft settings, I no longer see the checkmark and can enable this again.

The page I need help with: [log in to see the link]