Thank you! I was able to get that time slot for a group of 3 earlier today as a result of this. Strangely enough, it was just as you said. Online, if I selected 6, 7, or 8 people, the 8:45pm availability came up, but when I put in 3, I got the standard "no reservations available" message. So I called up the Disney dining reservation line and spoke with a rep there. Even more strangely, she said that for 3 guests, two times came up - it was like 7:45pm and 10:15pm - but the 8:45pm did not. I told her I was online right then and there and the 8:45pm was still "reservable" for 6, 7, or 8, but not for 3. She said she couldn't do anything on her end about it because that time was not showing up. I asked if it was possible for me to take that reservation for 6 and have her adjust it to 3. She said she would try. I kept her on the telephone line while I got the reservation for 6. The system came back saying the reservation was completed successfully. I gave the rep the confirmation number for the reservation and she immediately modified it to 3 guests. So all is well!
But I do wonder:
(1) Why I was not able to get the 8:45pm reservation for 3 guests online when 6, 7 or 8 were apparently available?
(2) Why that 8:45pm availability did not show up on the telephone rep's system when the online system was ready and able to accommodate as many as 8 guests at the time?
(3) Why did the other times that the telephone rep said were available for 3 guests when she checked (the 7:45pm and 10:15pm) not show up on the online system when I searched for 3 guests? (The online system's search came back with the message that it had checked between 6pm through 11pm and found "nothing" available.)