No throttle through APM

H all hope some one can point me in the right direction here. Have just updated my FX-61 from another FC to an APM 2.8 with the Arduplane 3.5 firmware installed. Motor will not spin up even in manual mode after APM has initialsed (ie pinged the servo three times) before that the motor will spin but as soon as APM gets set the motor cuts off. I have tried two different motors and ESC’s and both exhibit the same characteristic.
I have an older APM 2.6 with some earlier firmware installed for a long while now and this works flawlessly so am at a bit of a loss as to what is going on here. Please help anyone with any info

Thanks Hally

Now sorted since my last firmware and this one they implemented Arm/Disarm and I found it.