Are you trying to use 2048-pt IRs? You can only use one IR of this type per path, so if you have one in path 1, the other one must be in path 2, ie: you must split the signal from the amp before it hits the first IR.
There is a template patch in setlist 8 : 01B Parallel Spans, that illustrates the signal path, although it doesn't use IR blocks (But you can add them yourself after each amp block).
To access Setlist 8 on the device, push down the Preset wheel, then navigate using the joystick. In the Helix app, you should be able to access it by selecting Setlist 8 in the drop down menu, and then selecting preset 01B.