I was having very similar issues but for me the root cause turned out to be that I hadn’t set up my security keys in zwave-js-ui. After adding them, the sensors were added like a breeze.
When I first tried setting up my ring sensors, I would get a behavior similar to an above comment where HA said it successfully added the device but the device itself flashed red as if it didn’t agree. What’s worse, it seemed like zwave-js was constantly adding new versions of this device on an infinite loop, adding like 10 or so over the course of the hour that I spent debugging this. These were the first devices I tried to set up, so I wondered if it was the device or the server. I got a Zooz motion sensor to test it out and it worked perfectly the first time around… with the caveat that it showed a warning that the “Device was added insecurely”. All my other devices also failed to add securely, too. This was a big clue.
So I had set up HA on a docker container on my Synology NAS with a Zooz 800 USB stick for Z-Wave. For reasons related to that, I used zwave-js-ui in a docker container. One thing I had missed in the documentation was the Minimum Settings. Specifically the part to set up the zwave security keys! Once I had set those, the device that was adding failed devices on loop automatically got added securely and just worked from that point on.
tl;dr: Make sure secure inclusion is working. It’s possible the gen2 sensors don’t like being included insecurely.