Yeah I am having the same issue. I can book for my first day when I arrive Thursday January 5 but can't book for the entire vacation. Im guessing tomorrow I will be able to book for the 2nd day and so on. Today was my first day for 60 days out. Im on a 30min hold now for making reservations old fashion way. Its already very slim pickings for reservation choices. This is my first disney vacation since pandemic are last one was right last week of February when it was just starting. It's night and day different with restaurant availability compared to last time. Im definitely gonna have to get a service bot for checking reservations.
Saw the comment above how the system does a check for tickets. I don't have my park tickets yet I wonder if thats the case thats causing the glitch. We are at Saratoga Springs for 8 days.