I’ve had this strange problem on two different setups now.
One RPi2 with 2x iBuffalo Famicom-style controllers, and one RPi (B) with 2x noname SNES style controllers. In both cases, USB.
I configured one of them with “Register RetroArch controller” from RetroPie-Setup so I presume they’re configured automatically.
What happens is the second controller won’t work in some games unless I hold down a button on the first controller. Both controllers worked fine with Chip n’ Dale for NES, and TMNT tournament fighters for SNES, but not on Donkey Kong Country.
Has anyone experienced this? How do I fix it? Would manual controller setup fix it? :O 🙂