For any AFCS (in the broader sense of the word), to work, the Force Trim must be on, or the actuator will move the cyclic in the cockpit instead of the mechanics downstream to the rotor head.
I've never had any difficulty flying with force trim on all the time even in OH-58A/C or Bell 212. Wish the Jet ranger had it as basic kit, and we'd avoid a lot of later problems adapting to more complex machines.