Hi if you haven't all resolved the issue try this... in the universal control panel turn off loopback this allows you to record external channels without what is coming through the main mix allowing you to play tracks back and record new tracks simultaneously.
So like set up an audio trach/channel in reason i assign it to record channel one of mixer.I have a guitar plugged into channel 1 mixer.
Set a drum machine or synth to play in reason
With loopback set mix1/2 it will record the synth/drum machine and channel 1 mixer altogether onto on track.
With loopback set to off it will only record channel 1 of the mixer the guitar to the audio track of reason.thus allowing you to play back tracks and record tracks simultaneously.
So if you haven't resolved the issue yet hopefully this may help you.