autopkgtest-build-lxd reports "Error: not found", hangs, and then crashes

Hello,

Whislt using autopkgtest-build-lxd, I saw that the commands started to hang even though the output has been generated and then crashes, for example:

$ autopkgtest-build-lxd --help
Description:
  Create and start instances from images

Usage:
  lxc launch [<remote>:]<image> [<remote>:][<name>] [flags]

Examples:
  lxc launch ubuntu:18.04 u1

  lxc launch ubuntu:18.04 u1 < config.yaml
      Create and start the instance with configuration from config.yaml

Flags:
  -c, --config Config key/value to apply to the new instance
      --console[="console"] Immediately attach to the console
      --empty Create an empty instance
  -e, --ephemeral Ephemeral instance
  -n, --network Network name
      --no-profiles Create the instance with no profiles applied
  -p, --profile Profile to apply to the new instance
  -s, --storage Storage pool name
      --target Cluster member name
  -t, --type Instance type
      --vm Create a virtual machine

Global Flags:
      --debug Show all debug messages
      --force-local Force using the local unix socket
  -h, --help Print help
      --project Override the source project
  -q, --quiet Don't show progress information
  -v, --verbose Show all information messages
      --version Print version number
Error: not found
Timed out waiting for container to boot
Error: not found

$ echo $?
1

So when trying to build an autopkgtest lxd container via `autopkgtest-build-lxd ubuntu-daily:focal/amd64`, it hangs and then crashes.

Let me know if you need more information. TIA.