Weird Award Travel Availability on United

Last night I almost booked a flight from Syracuse to Vegas using mileage points. I hesitated since I not only had to change flights in Chicago (no non-stops from Syracuse ever), I also had to change in LAX. But, the flight arrived in Vegas early afternoon which is important to me.

I thought about it this morning, and decided to go for it. I did the LAX to LAS flight once before, and it was kind of fun; they fly relatively low over the Desert and it is a short flight. But, I went online and the earliest flight using award points got me into Vegas at 10 pm. Out of curiosity, I checked the United Android app on my phone and I was able to book the earlier flight. I checked online after, and I am ticketed and confirmed.

BTW, the early flight is still not available on the website using award points.

Any idea how this could happen? I guess I just assumed both the app and the website tap into the same database.