HI KV!
Sorry to disappoint you but some jockeys are not named even 2 hours or less before the race. It is just a fact, we have to live with it.
The trainer may nominate a jock (in hope only) when entering the nominations, but neither trainer NOR jock is under any obligation to proceed. Sometimes it's weight problem, sometimes better rides for the jock. The only certainties are bigger stables with stable jockeys.
Every data provider gets the info from the same original source, the difference is how often they are willing to update the info.
I use Cyberhorse subscription service, not because it's better then the free one but it's much faster and easier to download and at$250 a year not too dear, but even here I get more upto_date info if I download just the night before the race.