Auto cooling.. cura 4.8 win.

[aZiDtrip 0]

Hi,
i'm currently tuning my part cooling settings, and i think i found a bug.
i got a pretty good cooling setup where i'm able to get away with only 20% cooling on 8 sec layer times up to 45deg overhangs.
and i like to print with somewhat okay minimum speed at around 20mms.
So i adjusted my regular/maximum fan speed threshold to 8 sec. and my minimum layer time to 10 sec and min speed 20mms
On my test tuning model i get around 10-11 sec layer times and i would assume to fan speed would be at 20%, but thats not the case.. 
cura adjust my cooling speed to max set speed at 65 and stays that way all the way up to layer 73. then it adjust the fan speed down to 20%  even when the actual layer times are around that 10-11 sec mark..

anyone knows whats going on here ?