Definitely sounds like the anti-piracy thing.
It happened to a guy on a Fusion Discord server a few weeks ago, and this is what it looked like for him:
Here's how he identified it as a USB problem, and what he did to resolve that on Windows:
I see you're on macOS so port resets aren't an option. You could open Console then Start Streaming and search for USB to see if any errors pop up that might indicate the port disconnecting. Also maybe try another USB port, and trying cleaning the dongle's USB connector.
All that said, it's quite weird that it's not happening with Fu16. Have you gone from Fu16 immediately to Fu17 and tested and one works and the other doesn't? If there was a time gap between the tests, it could just be coincidental failing in one but not the other. Or maybe 17.x added extra checks on the USB dongle that make it more likely to fail than in Fu16, I'm not sure.