For the system to work properly (Shutdown / Reboot, etc.) one must choose MacPro5,1 as the Product Model in Clover SMBIOS. The one suggested by most Ryzen (especially for Opencore bootloader) hackintoshers, iMacPro1,1 is working but Shutdown / Reboot does not work. When one issues Shutdown, the system reboots!
Hackintosh Mojave Download