Setup not creating character mappings

[Bulmanator]

I have this setup with docker-compose and my file is as such:

    samba:
        container_name: samba
        image: dperson/samba
        networks:
            - default
        ports:
            - "137:137/udp"
            - "138:138/udp"
            - "139:139/tcp"
            - "445:445/tcp"
        environment:
            - TZ=${TZ}
        volumes:
            - "/mnt/mount_point:/mnt/mount_point:z"
        tmpfs:
            - /tmp
        read_only: true
        stdin_open: true
        tty: true
        restart: unless-stopped
        command: >-
            -w 'WORKGROUP'
            -c '0x3a:0xb7'
            -r
            -u 'user;${SMB_PASSWORD};1000;1000'
            -s 'share;/mnt/mount_point;yes;no;no;user'

However the character mapping (colon to midpoint) isn't added to the configuration.

When executing a shell into the running container and looking at the contents of smb.conf it does add the vfs objects = catia fruit streams_xattr values but there is no catia:mappings line which should've been generated by the charmap function in samba.sh upon startup.