EKF3,Optical flow and GPS behavior

Ηι @rmackay9
I have a more clean log from a calm day.

and the original from the other post is

to sum up:
a)If I power on with the switch to optical flow only and try to takeoff, I can climb up to an altitude (this varies from 40cm to 2m) and then it stops like it had an altitude fence. This happens both at loiter and alt-hold.
b)If I switch to GPS source I can fly normally
c)If I have a takeoff with gps source and then switch to optical flow only, I still can fly normally.
Any help is greatly appreciated, as with this behavior I cannot start the drone to a GPS denial environment, which is my intention.