My idle jet is clogged, so I have to keep rpm's up to avoid stalling while I ride. When the bike is cold or at least for the first part of the ride, I have no problem shifting from 1st gear to 2nd gear. However, once the engine temp comes up and I've been riding for a bit, it will get stuck in NEUTRAL as I try to shift from 1st to 2nd gear. If I let the RPM's drop, it will clear past neutral and go into 2nd (but I risk stalling because of the clogged idle jet).
The RPM's shouldn't matter as the clutch is engaged while trying to shift every time, right? Maybe its not the lower RPM's that help but rather the fact that the bike isn't moving as fast and bouncing around as much. The problem is definitely worse off road vs on a paved road.
It is not user error. I will usually end up jamming on it 5-6 times trying to get it out of first as my bike slows down until it stalls out. Sometimes it ends up in neutral, sometimes still in 1st. When this happens, I can shift into second while the bike is off, hold the clutch and start in 2nd, but I fall behind having to do this.

Any ideas why this might happen?