My right joy-con is not being recognized as connected into the switch.

I had this problem with my right Joy con not connecting wirelessly. I went into system settings, controllers and sensors. I then attached the joy con that was not connecting wirelessly to the switch. I then hit the disconnect controllers button and hit the X button. This allowed me to use the joy con wirelessly again.

I had the same issue after replacing the joystick. Turned out the bottom ribbon cable of the rail was not properly connected. Hope this helps!

"If I'm understanding you correctly, The joy con is connecting physically, but the switch isn't recognizing that it's connected?

https://en-americas-support.nintendo.com...

Nintendo recommends making sure your system has all updates to fix any firmware issues.

Then, try power cycling the switch, detach the joy con, reset the joy-con’s connection by pressing the Sync button and then a button on the controller. You should be able to attach it and the Switch recognize it. If it continues to happen, just the right joy-con would have to go in for servicing. The above link has the info for Nintendo repair services if you need it."

Hi, I had this problem with my left Joy-Con. I was playing FIFA 20 and the switch didn’t register the joy con physically connected. When I slid it in, It wanted me to press ZL on the joy con. I did that and nothing happened. I then restarted my Switch, slid in the joy con and the switch seemed to register it.

"I put a couple layers of painter tape on the switch side corner where the joycon slides down. These layers of tape pushed the controller outward helping the contact ribbons connect. try this!

It fixed my right controller not fully connecting."

The metal connection rail on the Switch can go faulty as well as the associated rail on the joycon. I think detection is made via NFC. If a known-good joycon does not detect then replacing the rail on the Switch can solve the problem.