Using the Dell open manage plugin with Nagios Core; fails to find server

I'm trying to monitor a Dell R730 server using the Dell OpenManage Plugin (https://www.dell.com/support/article/uk/en/ukbsdt1/sln311076/dell-emc-openmanage-plug-in-for-nagios-core?lang=en). I've got it built and it appears to run on the Raspberry Pi I'm using for the Nagios Core installation. I can connect to the server using the Openmanage utility from my desktop and can get information back from the server (opened port 161) using SNMPwalk from the rpi, using the command

snmpwalk -v1 -cpublic <ip_address>

It also works for the -v2c option. However when I try,

python dellemc_nagios_discovery_service_utility.py --host=<ip_address> --snmp.version=2 --output.file=/usr/local/nagios/dell/config/objects/

It fails to find the server, but appears to work;

Dell EMC device discovery is in progress...

Total no of Hosts / IPs provided :1
Total no of Hosts / IPs processed successfully :0
Total no of Hosts / IPs already discovered:0
Total no of Hosts / IPs processing unsuccessful:1

Dell EMC device discovery completed.

I used the instructions here, but couldn't get a version of the Dell RACADM deb for Raspbian. They're a bit old but I got most of it done.

https://www.dell.com/support/article/uk/en/ukbsdt1/sln310604/installation-of-dell-openmanage-plugin-for-nagios-core-on-ubuntu-os?lang=en

The plugin built fine and I installed the OMSDK using pip. None of the above commands were run with sudo, just as the pi user rather than nagiosadmin. This was the output from the install phase;

Dell_OpenManage_Plugin/Install $ sudo bash install.sh

Dell EMC OpenManage Plug-in v3.0 for Nagios Core requires Nagios Core v3.5.0 or later.
Press 'Y' to continue if Nagios Core version is 3.5.0 or later.
Press any other key to exit installation (default: 'Y'):  Y

Provide the installed location of Nagios Core (Press ENTER to continue with the default location: '/usr/local/nagios'):

        Using the default Nagios Core installed location: /usr/local/nagios
        Nagios Core installed location verified: /usr/local/nagios

Checking prerequisites...
        SNMPTT is installed.
        JAVA is installed.
        PYTHON 2.7.13 is installed.
        PYTHON argparse module is installed.
        PYTHON netaddr module is installed.

        OpenManage Python Software Development Kit (OMSDK) module is not installed or not appropriate.
Read the Dell EMC End User License Agreement (EULA) license file (license_en.txt) packaged with this product before proceeding with the installation.
Press 'Y' to accept the license.
Press any other key to exit installation (default: 'Y'):  Y

Installing "dell emc" Plug-in specific folders and files...

Enabling HTML tags...

The attribute "escape_html_tags" in file "cgi.cfg" is set to 1. Set it to 0 for better readability in Nagios Core console (recommended).
Press 'Y' if you would like to set it to '0' (default: 'N'): Y

Updating nagios.cfg...

        The following entry is added for configuring Dell EMC OpenManage Plug-in config directory:
        --------------------------------------------------
        cfg_dir=/usr/local/nagios/dell/config
        --------------------------------------------------

Provide the file path where snmptt.ini is installed (Press ENTER to continue with the default file path: '/etc/snmp/snmptt.ini'):

        Provided file path /etc/snmp/snmptt.ini is valid.

Updating snmptt.ini...


        The following entry is added for supporting Dell EMC device traps:
        ---------------------------------------------------------------------
        /usr/local/nagios/dell/config/templates/Dell_Agent_free_Server_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_Chassis_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_Compellent_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_EqualLogic_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_F10_Switch_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_N_Series_Traps.conf
        /usr/local/nagios/dell/config/templates/Dell_PowerVaultMD_Traps.conf
        ---------------------------------------------------------------------

Provide the file path where JAVA is installed (Press ENTER to continue with the default file path: '/usr/bin/java'):

        Provided file path /usr/bin/java is valid.

Updating dellconfig.cfg...

SUCCESS: Dell EMC OpenManage Plug-in version v3.0 is installed successfully.

For the Dell EMC OpenManage Plug-in changes to take effect, verify the Nagios and SNMPTT configuration entries as per product guidelines and then restart the Nagios and SNMPTT services.

Can anyone offer any pointers as to why this might not be working? I'm trying to work out if this is a problem with the plugin itself or a networking issue. If you need me to try and do anything to narrow this down, please ask.