I wonder what's the deal. What country are you from / in right now?
I'm in Israel on a mac using Chrome... Tried to book for 2 adults & two kids - tried multiple dates in April, multiple dates in May, tried Chez Remy, California Grill & Auberge de Cendrillon ... Nothing.
Getting: "Unfortunately this restaurant is not available (anymore) on the selected date. Select a different date in the calendar." (Used Google translate on the page)