Rekordbox <> DDJ-SR Mixer Mode Issue

Just recently purchased an old DDJ-SR controller. Was able to use all functionality within the Serato interface, but when connecting through Rekordbox I'm unable to use my controller to do anything within the software. I have downloaded all of the latest firmware and software recommended.

I am unable to switch from internal to external mixer mode when selecting Pioneer DDJ_SR Asio as the audio. Any ideas on how to help?