@cash0612 did you also change your PH temp? As you may recall I had based my 1kg off your method, but I introduced a soak at F1/P6 on charge for about 1.25 mins before bumming to P8 or 9 at F1 for another 30 sec before changing to F2. Eventually I switch to F3 and towards end F4. Seems to work for me.
I still preheat to 300C.
You can use a separate probe to monitor bean temperature: It’s possible that the I-R sensor on your Bullet may not be as accurate when roasting larger batches. Consider using a separate probe to monitor the bean temperature to ensure that it’s reaching the desired level.