SIEM - "All Hosts" Not showing Operating System

Hi All

I'm running Elastic, Beats and Kibana version 7.5.2.

In SIEM under the "All Hosts" tabs the servers are listed but the Operating System and Version is showing as a dash (-).

If I drill into the server it gives me a breakdown of the server in which case the Operating System is correctly showing as "Centos Linux" with version showing as "7 (Core)". If I mouse over these it shows "host.os.name" and "host.os.version"

The fact that the data populates in one view, but not another suggests to me it's a bug. Is this working correctly for other people?