Having the exact same problem. Syncing from Cura just sits there and spins. I can see traffic via my router going to/from the printer, but it still keeps spinning the syncing icon. Not sure what to expect at this point.
All I was really trying to do is sync a customized material profile that matches the 3DXTech CarbonX PETG+CF profile from the marketplace. I'm not using that one (not even installed) because it doesn't support the CC 0.4 nozzle (even though 3DXTech website says it's viable as a nozzle diameter).
And, following the USB method says there's no new material profiles...