Make sure you are using a stereo TRS mini jack in the OP-1 split into 2 mono TS jacks into your 2i2.
Yay for getting an OP-1!
Have you tried to plug another hardware to the same jack in on the scarlett ? Which line in do you plug ? Front or rear panel of the 2i2 ?
If not, you should try, and maybe check the mix control if there is one for this scarlett model.
Alright, just switched to a TRS mini jack split into 2 mono jacks and it works just fine.