Docker Volume missing after docker-compose down without -v flag


I have a pi with docker set up.
When running
docker-compose up -d --build
it will build my small server and initialize all custom log files (log4j).
What I want is to get the logfiles from the last execution, I missed to download them before shutting down the machine.

We stopped docker with
docker-compose down
As I understand the documentation this will also delete the containers but not the volumes.
To also remove volumes one need to ad -v flag.
Well under the expected path of
there are no volumes, only a metadata.db file.

In the docker-compose.yml we did not define a explicit volume (so i guess its an anonymous volume, which also is only removed with -v flag as I understand documentation).

So where is my volume? If it is deleted, why?
Thanks in advance

Raspberry PI
a020d3 B3+

Version: 18.06.0-ce
API version: 1.38
Go version: go1.10.3
Git commit: 0ffa825
Built: Wed Jul 18 19:19:46 2018
OS/Arch: linux/arm
Experimental: false