FocusRite Scarlet 2i for mic, getting monitor reverb

[lovelyllama]

Hello!  I recently set up Jamkazam on my computer for my fiance to use during his voice lessons.  I'm only using one input--the mic, so I configured the gear to use left-input only. However, the mirrored sound that he gets in the headphones has a slight reverb effect, as if the mirrored sound isn't quite synced up.

Direct monitoring on the 2i is turned off, and the headphones are plugged into the monitor port on the 2i.

Is there any way to fix this in the audio settings?  I'm very new to this software, so any and all help is appreciated!