I can’t hear surround sound in the LISTENTO plugin, using Reaper 6, what should I do?

LISTENTO plug-in supports up to 16 channels per plug-in instance.

If you have a surround audio track, but only see a 2-channel audio in the plug-in, that means not all inputs are being delivered to the plug-in. You will need to ‘send all keyboard input to the plug-in’ under the Reaper settings.