Reasnow S1 not working on Nintendo switch 2

[defy2744]

S1 firmware: 5.6.251
switch 2 firmware: 21.0.0

If I just connect the S1 to the dock, I can see the S1 booting into Switch mode in the app, but the Switch doesn't recognize the S1.
If I also connect the Pro 2 controller to the S1, the S1 will keep booting.

[Austin]

https://www.reasnow.com/download/ReaSnowApp/ReaSnow%20S1-UserManual.pdf
On page 7,
"For SWITCH:
1. Upgrade Switch System Version to the latest one
2. Disable Auto Sleep
3. then enable Pro Controller Wired Communication
4. A SWITCH Pro controller is not required.
If you have one, please do turn it off, while using ReaSnow S1 with SWITCH."
Please verify that you have followed these steps.