Edx is upgrading to Elasticsearch 7 and as result of it name of ELASTIC_SEARCH_CONFIG
setting has changed to ELASTIC_SEARCH_CONFIG_ES7
make sure you have set value of this setting in your /edx/etc/studio.yml
something like this
ELASTIC_SEARCH_CONFIG_ES7:
- host: edx.devstack.elasticsearch710
port: 9200
use_ssl: false
assuming your elasticsearch docker container name is edx.devstack.elasticsearch710