Due to a problem in the Intel® Quartus® Prime Standard Edition Software version 18.1, you may see the below error message when you reopen the existing IP for parameter editing.
Failed to launch MegaWizard Plug-In Manager. Transceiver Native PHY Intel Cyclone® V FPGA IP IP v18.1 could not be found in the specified library paths.
To workaround this problem, append the following alias to file <Quartus Installation Path>\ip\altera\alt_xcvr\altera_xcvr_native_phy\cv\altera_xcvr_native_cv_wizard.lst
<ALIAS>Transceiver Native PHY Intel Cyclone V FPGA IP v18.1</ALIAS>
This problem is fixed starting with the Intel® Quartus® Prime Standard Edition Software version 19.1.