@sch0s well, we will need mich more details to try to help you out. What specific issues are you having? And just to be sure... which one is the default core?
Don’t forget we don’t develop the emulator ourselves, so besides someone being able to confirm or deny the same issue happens on his/her installation, the libretro github issue tracker is the right place for you.
Humm it is a known problem with retroarch about keyboard/gamepad management.
Maybe by deactivating all gamepads in retroarch and allocating keyboard on player could solved this issue... Don't know, must be tried.
You can ask to libretro/retroarch team/community, they will be more informed that me.
The have have a forum/irc channel.
If you find informations to solve this issue, make us a feedback ;)