Ansible - Searching for a fixed reservation

Hi all, we are having trouble querying (with the .nios_lookup module). We are not able to look up and search whether an IPv4 address is reserved.

This is the request:
- name: "Query to check whether IP is reserved"     
ansible.builtin.set_fact:       
checkIfIpIsReserved: >-  "{{ lookup('infoblox.nios_modules.nios_lookup', 'fixedaddress',          filter={'ipv4addr': ipToReserve}, provider=nios_provider)}}"

This will successfully call to Infoblox but return an empty object. The documentation isn't clear by what values we can filter for the 'fixedaddress' type, so whenever attempting to filter by type (i.e. 'type':'Reservation') it fails. Does anyone know where I can read into how to search whether an IPv4 address is reserved?