Unable to retrieve IP from Bluecat using dhcp_bluecat smart proxy plugin

Problem:
I’ve configured dhcp_bluecat.yml (and dhcp.yml) as described in documentation. I’ve tested API calls used and API user authentication with Postman against bluecat server directly.
When I select a subnet configured to use DHCP, I receive an error that an IP address could not be requested, error 400 from the proxy.

Using curl directly, I simply get:
undefined local variable or method 'c' for # <Proxy::DHCP::BlueCat::PluginConfiguration:0x000055d9df093cb0>

Expected outcome:
I get an IP address or some meaningful message to help me troubleshoot.

Foreman and Proxy versions:
Foreman 3.8.0 + Katello 4.10.0. Proxy is running on the Foreman server.

Foreman and Proxy plugin versions:
rubygem-smart_proxy_dhcp_bluecat-doc-0.1.6-2.fm3_3.el8.noarch
rubygem-smart_proxy_dhcp_bluecat-0.1.6-2.fm3_3.el8.noarch

Distribution and version:
Rocky Linux release 8.8 (Green Obsidian)

Other relevant data:

[I] Started GET /dhcp/10.43.192.0/unused_ip from=10.43.192.0
[E] undefined local variable or method `c' for #<Proxy::DHCP::BlueCat::PluginConfiguration:0x000055d9df093cb0>
2023-11-15T15:30:06 b2eb979b [W] Error details for undefined local variable or method `c' for #<Proxy::DHCP::BlueCat::PluginConfiguration:0x000055d9df093cb0>: <NameError>: undefined local variable or method `c' for #<Proxy::DHCP::BlueCat::PluginConfiguration:0x000055d9df093cb0>
/usr/share/gems/gems/smart_proxy_dhcp_bluecat-0.1.6/lib/smart_proxy_dhcp_bluecat/plugin_configuration.rb:29:in `block in load_dependency_injection_wirings'