Mac OSX shows ‘Listening’ under the Clock Status tab in Dante Controller
In some Mac OS X and switch configurations (notably in OS X 10.13) IGMP snooping can interfere with PTP traffic to the computer’s network interface. This can prevent DVS achieving PTP sync with the network, which in turn prevents reliable audio transmission.
The easiest solution is to ‘Forward All’ multicast to the Mac. In effect, that disables IGMP snooping for that port. However, assuming the Mac has a Gigabit port, you should be fine.