Left ear Only?

[Rott3n Hippi3 (Hippie)]

I brand new to Sonobus in an attempt to have band practice via remotely. I've run into a rabbit hole trying to figure out how/why I can't get my guitar player in both ears.  He's set to MONO on his end and my output on his track is set to my Headphones 1-2, yet any panning options disappear and I"m stuck with just left ear.  If he changes his output to stereo, then I get panning options, but its still the same... toggle all I want, I'm just going to get left ear.  I feel like the issue is on my end, but I'm totally lost.  Or does SonoBus just assign left/right based on how many users are connected? Meaning, if I had another guitar player connected, then that would open panning options. I'm worried I'm going to have both guitars plus bass only pumping through left ear once we're all setup. Advice is appreciated!!!!