Kibana, the software running logstash.wikimedia.org, as well as elasticsearch, the server behind the scenes storing all the logs, have both been upgraded today to their latest versions. Several historical indices could not be directly loaded into the new servers and instead have been dumped and are being reloaded. This reloading process may take some time, so please be patient. The data will be there sooner or later :)

Play around with them, and create tickets in the wikimedia-logstash project for any issues you find.