I'm trying to record audio for the first time and it's recording only on the left track. I don't have this problem with other recording software (such as Garage Band). The VU Meter shows a signal only on the left. I hope this is an obvious beginner problem. Can anyone help? Thanks!

Mac OS Sierra 10.12.6
BB 2017 (186)
Focusrite Scarlett 18i8 using input "Analogue 1"