Visibility Based Anim Tick Option issue with some (modular) NPCs

It seems like the ‘Visibility Based Anim Tick Option’ optimization doesn’t work with modular characters, or with characters that have been mesh-merged. Basically, for these characters, only the ‘Always Tick Pose and Refresh Bones’ option works. For all other settings, my characters stay in a T-pose, even when they’re clearly visible and rendered on screen. Is this expected behavior, or is there a trick to optimize this setup?