I have tested the functionality without any issues.
Can you please let me know if you have modified the application?
Also, please make sure that the below conditions are met:
1. SCB is configured to SPI CDC Master and the COM port is enumerated in the device manager.
2. COM port is bound to USB-Serial Port Driver and not USB-Serial Device Driver
3. Proper jumper settings are made on the DVK, as per Figure 3-36. SCB SPI Jumpers in CYUSBS236 Kit guide
4. The correct COM port number is passed as input to the application.