Sadly I’m still struggling with this (same on Copter 3.5 RC9).
I’m wondering if there is a particular reason why the flow_enable parameter is changed when the optical flow isn’t detected? This doesn’t seem like standard behaviour for external devices - e.g. if copter is booted without GPS or rangefinder, no parameters are changed so when they are re-connected everything works again…
On a separate note, I’ve just been testing AC3.5rc9 using GPS blending, Optical flow and laser rangefinder… the position hold accuracy is seriously impressive now. Really incredible work!
Justin