The Intel® FPGA USB Download Cable may not be detected by Intel Quartus® Prime Programmer even when it is recognized correctly in Device Manager because the version of JTAGServer running as a host is not working properly as a user mode application.
To resolve this problem, use the following steps:
1. Run Windows in SAFE MODE
2. Run “msconfig” in command prompt to bring up System Configuration Window
3. In Service tab, disable “Altera JTAG Server” and then reboot the PC.