After discovering a CiscoAPIC device in Spectrum the interfaces tab returns "This model had no interfaces".
Cisco does not put APIC interface information in any MIB object.
Due to the lack of interface information in any supported MIB, Spectrum is unable to discover the interfaces.
For more information on supported MIBs for CiscoAPIC, please see this link:
Broadcom suggests utilizing Virtual Network Assurance product to monitor and handle APIC devices.