I have been troubleshooting a bit with Solarwinds NCM and Fortinet Firewalls. There are several different commands you can run to get configuration information from a Fortinet Firewall. You can run "show", you can run "Show full-configuration", however, Orion doesn't seem to get the same output as if a user were to run the same command. I found if you go into your Fortinet template in NCM and change the "DownloadConfig" Value to "sh" you will get the entire Fortinet configuration including the policies.
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<!--SolarWinds Network Management Tools-->
<!--Copyright 2005 SolarWinds.Net All rights reserved-->
<Configuration-Management Device="FORTINET FORTIGATE 1000A" SystemOID="1.3.6.1.4.1.12356.101.1.10001">
<Commands>
<Command Name="RESET" Value=""/>
<Command Name="DownloadConfig" Value="sh"/>