There are a few common things that can cause the Apollo 8 & Apollo 8p to not be recognized by the computer. Here's what to check if you're getting the 'No Devices Found' message in the UAD Meter:
Check Thunderbolt Cable Orientation
When connecting Apollo 8/8p to the computer always check the orientation of the Thunderbolt cable. The Thunderbolt logo must be face up on the Thunderbolt cable when plugged into both the Apollo 8/8p and the computer - if the Thunderbolt logo is not face up then the cable is inserted upside-down, which can be done fairly easily.
Note: On iMac computers, the Thunderbolt logo on the Thunderbolt cable should face left (when looking at the back of the iMac).
Check Computer Compatibility
Apollo 8/8p cannot be used by connecting it to a Mini DisplayPort connector. Although Thunderbolt and Mini DisplayPort devices have the same physical connector, the underlying communication protocol used by these devices is different and the Apollo 8/8p will not be recognized when connected to a Mini DisplayPort.
The type of device port can be determined by the icon next to the port. Thunderbolt ports have a "lightning bolt" icon, while Mini DisplayPort ports have a "display" icon. The difference between these ports and icons is shown in the illustration below.
Still having trouble? Check out the Apollo 8 & Apollo 8p Basic Troubleshooting article.