Kickr, iMac, Garmin ANT+ stick

I just got a Wahoo Kickr 17, and I’m trying to pair it to my iMac with a Garmin ANT+ dongle. When I open Zwift, it only wants to pair to the Kickr via bluetooth.
I know the drivers for the ANT+ are good and working, as it can pick up my heart rate monitor via ANT+. But it’s not giving me the option to select ANT+ when connecting the trainer, even having unpaired the heart rate monitor. What am I missing?   

Also worth noting, I updated the firmware on the Kickr when setting it up.

Is your computer within the trainer’s ANT+ range?

D’oh! Looks like I’ll be needing an extension cable. Thanks!

Do you have an ANT-USB2-Dongle? I had an old Garmin-Dongle with a “USB1” description on the backside…(from older edge series) --> Not supported. 

I guess I have a USB2 dongle then, as the issue was caused by what Paul mentioned. I’ll be needing a USB extension cable because the trainer is too far away from my computer. Thanks for the help guys!