These appears to work for me now. The aforementioned solution of completely removing all the pre-existing controller .cfg files and making it so only my USBGamepad.cfg was the only file in the directory seems to have fixed it.

I’m making a few of these for gifts (including controllers) so I don’t see an issue with removing all those pre-existing files, but it would be nice to know a solution that doesn’t involve that.

Thanks all!