I'm using...
Ableton Live 7.0.1.
Reason 4.0
Novation Remote 61 SL 4.1
Order to reproduce issue:
1. Launch Ableton
2. Launch Reason
3. On Remote, switch to Ableton Template; move sliders, play keys and it appears on screen.
4. On Remote, switch to Reason Template; move sliders, knobs and it appears on screen.
5. On Remote, switch back to Ableton Template and you'll notice you lose MIDI control and moving sliders or playing keys does not show on the screen.
Note: When you manually move the slider with mouse on the screen, the values DO change on Remote's display.
When I revert back to Live 6.0.10, Remote works fine, but then I run into a different issue.
Reproduce the issue with 6.0.10:
1. Drag Midi file into Ableton
2. Route Ableton to Reason to play Midi
3. Hit Play and you'll hear notes being held instead of each note being played.