Hello && Welcome @Alex25
You will have to wait till Elasticsearch gets done, noticed this.
Depending on your resource this may take some time.
Also when Output Buffer are over 90% chance ar this may be a configuration error in Graylog config file or you don’t have enough resource to handle that many logs.
I would serious look into you Local log file to see if there are any errors or warning.
examples
tail -f /var/log/graylog-server/server.log
tail -f /var/log/elasticsearch/graylog.log
curl -XGET http://192.168.1.100:9200/_cluster/health?pretty=true
I don’t read/speak Russian.