This doesn't seem to really make sense here - the output is a hash and the summary plugin doesnt do well with that as its key=val orientated, the output on the CLI looks like:

<pre>
devco.net
   Value: {"fqdn"=>"devco.net", "operatingsystem"=>"CentOS"}


Summary of Value:

   fqdndevco.netoperatingsystemCentOS = 1


Finished processing 1 / 1 hosts in 49.93 ms
</pre>

Because this isnt key=val data, best is probably just to remove the summarize block here