Update. I found the new culprit. I had a bad USB cable connected to my MCU8. The cable registered ‘connected’ by my PC but may have been shorting signals needed for proper functioning. My MCU is now working fine on either USB2.0 OR 3.0. 
Update. I found the new culprit. I had a bad USB cable connected to my MCU8. The cable registered ‘connected’ by my PC but may have been shorting signals needed for proper functioning. My MCU is now working fine on either USB2.0 OR 3.0.