Due to a visual problem in the Intel® Quartus® Prime Pro Edition Software, we might see EMAC A setting change from RMII to RGMII in Intel® Agilex™ FPGA HPS IP Pin Mux GUI when clicking the other IP in the Platform Designer and back. In fact, the RMII interface setting is valid and we can reference the Advanced IP Placement for RMII interface I/O assignment.
This problem is scheduled to be fixed in a future release of the Intel® Quartus® Prime Pro Edition Software v23.1.