I have the same macbook and OS and my Ant+stick doesn't work at all on it, I have to use bluetooth instead.
Did you try a USB extender cable?
I've tried 3 different usb-c to usb-a adapters and none worked, including powered ones.
@hippy started
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I have the same macbook and OS and my Ant+stick doesn't work at all on it, I have to use bluetooth instead.