500: Cache store [] is not defined (docker-image)

booted up, setup completed, trying to login (mainsite works)

.env: (the one inside the docker container, changes in the `cachet-docker/conf/.env` seem to be ignored
```
APP_ENV="development"
APP_DEBUG="true"
APP_URL="************"
APP_LOG="errorlog"
APP_KEY="************"

DB_DRIVER="pgsql"
DB_HOST="postgres"
DB_DATABASE="postgres"
DB_USERNAME="postgres"
DB_PASSWORD="postgres"
DB_PORT="5432"
DB_PREFIX="chq_"

DOCKER=true

CACHE_DRIVER="file"

SESSION_DRIVER="file"
SESSION_DOMAIN="************"

QUEUE_DRIVER="sync"

CACHET_EMOJI="false"
CACHET_BEACON="true"
CACHET_AUTO_TWITTER="true"

MAIL_DRIVER="smtp"
[.....]
MAIL_NAME=null
MAIL_ENCRYPTION=tls
MAIL_PORT="465"

NEXMO_SMS_FROM="Cachet"
```


Any advice?

Also yes, I did run the artisan config:clear command every time after changes.