A new Nintendo Switch firmware update (Version 4.0.1) was recently released to fix HDMI issues that some players have encountered playing in TV Mode.

This update has also caused a small issue with the Wii U GameCube Controller adapter. Players may find the Switch unable to detect the Wii U GameCube Controllers  after the update is installed.

To solve this issue, simply re-detect the controllers in the Controllers section (found on the HOME Menu).