How do I know the "No arrivals" setting has been saved? It is unchecked when I go back to same date.

I would like to make sure nobody arrives on a certain day, as I'm out for a couple of hours in the evening.

However when I check the option (in Advanced restrictions) 'No arrivals' and click Save, and then go to a different day and come back, the 'No arrivals' setting is unchecked.

Perhaps it has been taken into account, but how can I tell? 

Is it a bug in the website?