I have exact same problem but not with canopy. My network has a mix of cpes from different vendors, the majority being ubiquiti. Every Ubiquiti device is discovered correctly on every scan without fail, as is other vendors except one. Believe it or not I have trouble with the microtik devices on my network. Like you I can manually add the nodes to a map and they are monitored fine, The dude just will not discover them during an Autoscan. I have gone through the CPE configs time and time again with no idea why this is happening. I am beginning to think there is a problem with mixing CPEs from different vendors but cant understand how that could be.