I am experiencing the same (I think). I can't get the cosmos to start up. Opening the VIVE console only gives me a 205 error with no possibility of waking up the headset, no matter how much I clear or restart it. The light on the cosmos stays red all the time and I've only seen it turn green for a very brief moment once. Pairing controllers works fine.
The 1.2GB cosmos software download also doesn't start/complete, but the former one (which is about 600mb) does. I didn't think it was much of an issue but here I am with a useless headset. I also don't notice windows installing any device drivers - there's no popup in the task bar or anything but USBDeview does show the USB devices but they all use the regular windows drivers from 2006.
I did notice that connecting the headset and turning on the power enables most USB devices, but the audio ones disconnect short thereafter (also reflected in USBDeview). Surprisingly, it does seem to work for as short as it does as the audio sometimes does come through the headset and then immediately disconnects again.
If the cosmos drivers indeed are not downloading then I hope this gets fixed, but if it's somehow related to my mobo/usb ports then I'm afraid I'm screwed. I'm going to try and disable overclocking and flashing the bios tomorrow to see if that helps anything, but the 205 error seems to signify that something in the software is not working as intended.
I'm running Windows 10 1909 on a Vega 56 and a MSI Hawk B450 mobo with a Ryzen 2700 OC'd to 4ghz. Haven't had any USB or system problems before and Windows MR worked perfectly fine.