G-SPEED Shuttle T3 EV Series not seeing ATOMOS SSD

I just purchased the 24TB G-SPEED Shuttle XL Thunderbolt 3 with 2 EV Carrier slots. I purchased 2 EV carriers and when I insert them (without a drive), the unit detects the 2 EV carriers. If I insert my ATOMOS 4TB SSD enclosure into the carrier, nothing happens–does not detect the drive. If I pull the carrier out and plug in a thunderbolt 3 cable and connect it directly to my Macbook Pro, the computer sees/mounts the drive properly. I tried the SSD in both carriers, in case one was faulty, but same behaviour (or lack of). Any thoughts/tips? - Thanks, Frank.