I have been using my third-party "GameCube Controller Adapter for Wii U & PC" on my Switch with no issues for almost 6 years. When I went to use it today, there was a problem: all of my games now register my left analogue stick (the grey one) as the Directional Pad. When I go into Smash settings to check it out, the analogue stick doesn't have a custom option at all (no blue outline).
My current setup that I've tried alternating is
>grey USB stick on bottom, black USB stick on top
>controller adapter switch is set to "PC" (no response when set to "Wii U")
pic rel is what I believe my adapter is (Mayflash GameCube Controller Adapter for Wii U, PC USB and Switch, 4 Port)