Mapping a real N64 Controller - Ripping my hair out!

I have tried everything to get my N64 Controller mapped in both Mupen64plus and Parallel. I am using a USB converter. I can map the majority of the buttons but can not get the C-Down and C-Left buttons working properly.

I’ve read every post I could find related to this issue. The weirdest part is, after trying for a couple hours, I started to fiddle around with the retroarch input mappings on top of the core control mappings and eventually got it working, somehow (pure luck) - or so it seemed. I saved everything and restarted retroarch only to have the controller not register anything at all.

Reset retroarch settings and now I am at square one trying to get all the buttons mapped properly. Has anybody had any success with this? I wish the cores allowed for easy button mapping!

There’s a core option, “independent c-button mapping” or something like that, which will put all of the C-buttons onto digital buttons instead of the analog sticks, which makes it a little simpler/easier to remap, particularly onto real controllers.