Can't use joystick when autothrottle armed but no speed mode selected

Dear PMDG, Congratulations again on the release of an amazing aircraft. When on approach and flying by hand, I like to deselect the speed mode (MCP SPD) and manually control the throttles whilst still keeping A/T ARM on. This apparently provides some degree of stall protection. However, in the NGX I am unable to use my joystick's (CH yoke; configured via FSX) throttle lever until I also turn the A/T ARM switch off. Note that after I turn MCP SPD off I can manually adjust the throttles using the F keys on the keyboard, just not using the throttle lever on my joystick. Is there a way I can configure my joystick so that this works? If not, perhaps could you fix this in a future service pack? Thanks,