We did the exact same thing you are trying to do last summer, and it was my first and only time I tried to schedule a pick up in advance. I did it the night before. It showed our request went out and confirmed it, but no driver. I think we had a 5 a.m. pick up.

At 4:30 a.m. I checked and there was still no driver. Same at 4:45, and at this point I had to wake another person at home and ask them to drive us. Right about that time, we had a message our request had been cancelled. So we all piled in the car to leave.

As we were leaving at 5 a.m., I got a call from an Uber driver who was on the way and 15 minutes out. First, that would have made us late. Second, it showed our request had been cancelled. And third, we had a 5 a.m. pick up and it was now past 5 a.m.

So I said thanks but we are already on the way. Uber charged US a fee for a cancelled reservation. I debated fighting it, but we were on our way to Aruba and I didn't have the energy, and those Uber drivers don't make a lot. So I didn't.

But yeah, you are right to be concerned. None of what we experienced made sense.