Environment variable not passed into apprise-api container

I noticed that when setting APPRISE_CONFIG_LOCK in the docker compose file apprise-api was not locking config. I went into the container and noticed that APPRISE_CONFIG_LOCK is not being set:

services:
    apprise-api:
    image: lscr.io/linuxserver/apprise-api:latest
    container_name: apprise-api
    depends_on:
      - nginx-proxy-manager
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Sydney/Australia
      - APPRISE_ATTACH_SIZE=5
      - APPRISE_CONFIG_LOCK
    volumes:
      - /data/apprise-api/config:/config
      - /data/apprise-api/attachments:/attachments
    ports:
      - 8000:8000
    restart: unless-stopped

Inside the container:

➜ docker exec -it apprise-api bash
root@13de2a118cab:/# export
declare -x APPRISE_ATTACH_DIR="/attachments"
declare -x APPRISE_ATTACH_SIZE="5"
declare -x APPRISE_CONFIG_DIR="/config"
declare -x HOME="/root"
declare -x HOSTNAME="13de2a118cab"
declare -x LSIO_FIRST_PARTY="true"
declare -x OLDPWD
declare -x PATH="/lsiopy/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
declare -x PGID="1000"
declare -x PS1="\$(whoami)@\$(hostname):\$(pwd)\\\$ "
declare -x PUID="1000"
declare -x PWD="/"
declare -x S6_CMD_WAIT_FOR_SERVICES_MAXTIME="0"
declare -x S6_STAGE2_HOOK="/docker-mods"
declare -x S6_VERBOSITY="1"
declare -x SHLVL="1"
declare -x TERM="xterm"
declare -x TZ="Sydney/Australia"
declare -x VIRTUAL_ENV="/lsiopy"
root@13de2a118cab:/#

How do I set APPRISE_CONFIG_LOCK

Disregard - turns out you have to enter it as:

APPRISE_CONFIG_LOCK=1

A blank env variable is not parsed