This is strictly a guess because it has happened to me previously with dining ADRS - assuming you live in the US - are your settings set to US ( English) ? Sometimes they change on their own ( mine always goes to Canada , and then I can't book anything !
I was ready yesterday morning first thing and had 2 computers going. I couldn't sign in on windows edge but could on explorer. Then when I tried to do a reservation I couldn't pick a day in my reservation week. This went on for 15 minutes. I decided to try windows edge again and after about 20 times signing on and getting kicked out I finally got signed in and made my reservations. People like us in this group put a lot of time and effort into "perfect trips" and it is hard to take when Disney's end of it screws up. My dining reservations worked but if this was fast pass day that 15 minutes delay might have meant not getting what I wanted.
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