The Octa out to Axe rear Input 1 connection could be considered optional. It would only be useful if you want to send tracks from Octa through the Axe again, e.g. reamping, and there are other ways to accomplish that.
If it's not something simple like volume control at 0, the no sound at Octa outs 1/2 issue might be due to some setting in its mixer/control software. Or Reaper could be set to use outs 3/4 as main output.
If it's not something simple like volume control at 0, the no sound at Octa outs 1/2 issue might be due to some setting in its mixer/control software. Or Reaper could be set to use outs 3/4 as main output.