Greengrass in docker starts but then fails when deploying a lambda function

I'm trying to run greengrass in a docker following the instruction here:
https://docs.aws.amazon.com/greengrass/latest/developerguide/run-gg-in-docker-container.html

I'm running in virtualbox instance:
Ubuntu 18.10
docker 18.09.4

The bind mounts didn't work using "-v"

docker run --rm --init -it --name aws-iot-greengrass \
--entrypoint /greengrass-entrypoint.sh \
-v /tmp/certs:/greengrass/certs \
-v /tmp/config:/greengrass/config \
-p 8883:8883 \
216483018798.dkr.ecr.us-west-2.amazonaws.com/aws-iot-greengrass:latest

If I replaced -v with --mount type=bind,... It works.

I didn't want to explore why -v failed... a later concern

My GG daemon starts and runs, but then dies when I deploy my lambda function.

I'm getting the error in the runtime.log
[2019-04-06T22:57:00.387Z][INFO]-Setting up worker process factory
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: hugetlb
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: freezer
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: pids
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: cpuset
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: memory
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: rdma
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: devices
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: blkio
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: perf_event
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: net_cls
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: net_prio
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: cpu
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: cpuacct
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup: name=systemd
[2019-04-06T22:57:00.389Z][INFO]-Found cgroup:
[2019-04-06T22:57:00.518Z][FATAL]-Failed to reset thread's mount namespace due to an unexpected error: "operation not permitted". To maintain consistency, GGC will crash and need to be manually restarted.
^

My lambda config is set to run with "No Containerization" using ggc_user/ggc_group
(lambda function is python hello world example)

I don't know what this error means. Any pointers?

Thanks!