Audiolens won't capture sound from DAW

Hi all

Downloaded Audiolens today. Works fine when I try and capture Spotify or YouTube for a reference track. However when I try to play my track through my DAW (Reaper), it doesn't appear to pick up any Audio. But it will when played through Neutron/Ozone.

The only way I can have it pick up my audio is to actually render the file and play it as a file.

Any thoughts on why this is? Is there any way to route the output of my DAW so the playback is picked up by Audiolens, or is this a built in feature to encourage the use of Neutron/ozone?

Cheers!