Not enough lather for the third pass

Need more water. Shaking too much out of the brush.
 
You need more cream and or more water, I would guess if your lather was good but just not enough for 3 passes that you just need more cream to start with. P.
 
Try bowl lathering a couple of times: load by swirling 10 times, 20 times, 40 times and compare how much lather is then produced in bowl, no magic going on it is just at matter of soap + water + whip it good = lather
 
Remember that there's no rule that states 'thou must complete the shave with a single load'. I've reloaded for a third pass on occasions. There's also often a good amount of lather within the brush that can be squeezed out to help complete the third pass if you don't want to reload.
 
Hi, I'd think you need more cream. I'm always amazed by those who can lather well with a pea size amount! Depends on tge water i suppose.