Mountpoint ignored?

[mplx]

I'm stuck on the mountpoint opt in my docker swarm - I'd like to mount /mnt/app/volumes/data but as docker inspect shows the source dir sticks to the stacks yml file directory...

• Expected: mount /mnt/app/volumes/data to /data
• Happening: mounted /mnt/app to /data
• Docker version 17.10.0-ce (f4ffd25) on Debian Stretch
• md5sum /usr/bin/docker-volume-local-persist 815b4b931c92af3eb5417a74bf07fd35

cat /mnt/app/compose-stack.yml

version: "3"

services:

  app:
    volumes:
      - appdata:/data
...

volumes:
  appdata:
    driver: local-persist
    driver_opts:
      mountpoint: /mnt/app/volumes/data

docker stack deploy -c /mnt/app/compose-stack.yml app

docker inspect ID

...
            {
                "Type": "volume",
                "Name": "app_appdata",
                "Source": "/mnt/app",
                "Destination": "/data",
                "Driver": "local-persist",
                "Mode": "",
                "RW": true,
                "Propagation": ""
            }
...

[CWSpear]

I'm not sure how this could happen. Did you figure anything out about it?

Possibilities on the top of my head: other volumes trying to use the same space that causes an issue? Are any symlinks involved? I think it should work with symlinks, but I haven't really tested. Just throwing out ideas here.