Check your Prefs-Audio settings.

If you are trying to record a single MONO track (5) make sure the option for 'Input Channel for MONO Tracks' is set to either Left channel or Right channel.
From your clues it sounds like you want to record the left and not the right. I assume left is 5 and right is 6.

So set it to Left only .. see if that helps.
This is assuming the tracks are MONO tracks, but that's the most likely scenario for this occurring.

Edit to add image

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Last edited by rharv; 02/07/18 02:26 PM.

Make your sound your own!
.. I do not work here, but the benefits are still awesome