Due to a problem in the Intel® Quartus® Prime Pro Edition software version 18.1 Update 2 and earlier, Platfrom Designer may fail to generate the system when Parallel IP generation is enabled.
To work around this problem, disable Parallel IP generation in Platform Designer. Configuration is available from menu Plaftom Designer menu Generate/ Generate HDL or you need to use option --parallel=off on command line.
This problem has been fixed in the Intel Quartus Prime Pro Edition software 19.1 version.