Deviations between monthly and quarterly Gong projection

Hey, we’re using the Gong projection quite a lot in order to test the bottom up forecast of our leaders. 
One issue we just came across is that when comparing the sum of monthly projections within a quarter with the quarterly projection we get two completely different numbers. 

For example, our Q3 projection is currently 24% higher than the sum of July, August and September projection. The weighted pipeline amount is 12.5% higher, the expected deals amount 38.7% and the applied win rate on the expected deals is a whopping 13%-points higher than the average of the three single months. 

While I understand that there might be slight differences when aggregating the data these difference seem to be too extrem and reduces the confidence in the quarterly number, especially since the monthly projection seem to be closer to the bottom up forecast. 

Could someone explain where this large difference is coming from and why e.g. applied win rates are so extremely different?

Thanks!