Template Lock problems

[heavy fjord]

I have a Zigbee lock (lock.back_door_lock) that receives and performs lock and unlock commands just fine. But it always has the "unlocked" status. I figured that one way around it is to create a Template Lock that forwards commands to the lock and is optimistic. Here is the code I've used. But its status too is always "unlocked," regardless of whatever the most recent command is.

lock:
  - platform: template
    name: Back Door Lock Optimistic
    optimistic: true
    value_template: "locked"
    lock:
      service: lock.lock
      target:
        entity_id: lock.back_door_lock
    unlock:
      service: lock.unlock
      target:
        entity_id: lock.back_door_lock