Mounted volumes on host after container started does not propagate to the container with propagation set to rslave

I am using the Docker package of Synology DSM 6.2. While the WebUI of the Docker support volume of container with rprivate in propagation only, I managed change the values of propagations of some volumes of a container to rslave by editing the container configuration file by hand and start the container via ssh.

The ISO images I mounted before the container starts are shown in the container fine. However, the ISO image I mounted after the container started are not there in the container. Is this a known limitation? Or is it a bug of the Docker package of the DSM? The docker version of the DSM is “18.09.8, build 2c0a67b”.

Steps to reproduce:

  1. start a container with option --mount type=bind,source=/volume1/media/,target=/mnt/media,propagation=rslave
  2. run the following command on the host mount -o loop /volume2/dvd.iso /volume1/media/dvd
  3. run the following command on the container, ls -l /mnt/media/dvd

Expected result:

  1. the content of the iso image are listed.

Actual result:

  1. the directory is empty.