It sounds like you’ve already done it, but just to make sure, you did this process?
After you’ve done that, you may want to go to the “Devices” screen, click “Add Devices,” scroll to the bottom and click “Other,” then click “Discover Devices.”
If you’ve done all that, do you still have Wyze devices which aren’t showing up in Alexa?
One other thing you could try is re-pairing the device in the Wyze app also. I’m not sure if it would be necessary, but it seems like a good troubleshooting step to try.