Mity CPU Platforms » MitySOM-5CSX Altera Cyclone V

I've been able to get a successful connection b/w the HPS RGMII EMAC with an external PHY, but my design also uses a mitySOM that connects to a KSZ9897R's MAC interface port (so an HPS RGMII EMAC connection to an external MAC interface). When testing this mac-to-mac connection I seem to be able to transmit from the MitySOM TX lines, but I cannot receive anything on the RX lines. Could this have anything to do with the MitySOM or Cyclone V not supporting an external MAC interface? When reviewing Intel's Cyclone V documentation I only find advice on the HPS EMAC connection to external PHY interfaces.