At least for me banging around for a couple hours and getting no where, because what I was doing, there was 0.00000000% success rate.
I was trying to Remap a 6 button Sega Saturn Controller to use with my SegaCD/MD/GEN/Saturn Emulator. In which I mapped most fine but for the life of me I could not map C ever.
Long story short. (Make sure you map ALL your buttons in the config, even if its something backwards like C=-yaxis or C=L trigger ect. Because I had most buttons then what it wanted to map in the GUI I just skipped. And well you can RE-map a button that has not been mapped in the first place. So after banging my head on my desk for hours, I got it to work when I bound C on my sega saturn bad to L trigger, then remapped it in the core options.
I am not sure if the “AutoMapping” or AutoConfig does the mapping of all the buttons for you and assigns them as such with a default value, I just went by my manual mappings, which is why everyone’s button config will vary depending on what you mapped it too first.
Most people might already know this or this is common and do not have to even think about it, it was just odd that I missed the entire first step and was working on 3-4th step, all to get the C button to work.