I've also recently setup an instance of TIBCO Jaspersoft for AWS with Multi-Tenancy and changed the .../WEB-INF/applicationContext.xml enableSaveToHostFS to TRUE.
I've restarted tomcat, even restarted the servers involved and yet the web ui still shows the Output To File System option as greyed out.
I eventually found that the AWS auto scale group had created and made active a second server so I updated each of these files:
/var/lib/tomcat7/webapps/jasperserver-pro/WEB-INF/applicationContext.xml
/usr/share/jrs_dist/jasperreports-server-bin/buildomatic/conf_source/iePro/applicationContext.xml
/usr/share/jrs_dist/clusterConfig/applicationContext.xml
I then restarted tomcat and everything worked!!!
next problem is "Enter a valid path." but this seems to be a permissions thing.
