Always consult the Owners Manuals
From Axe-Fx II Wiki
When there's no sound
If a preset doesn't produce any sound, check the following:
- Connect grid input to grid output through blocks or shunts.
- Bypassed blocks: bypass mode is not set to “Mute”.
- Blocks are in the correct X/Y state or channel.
- Amp block, Cab block and FXL block: not bypassed.
- Cab block doesn't link to an empty user cab slot.
- Volume block with attached controller is not set to zero volume.
- Device has latest firmware.
- Output level knobs on hardware are turned up.
- FX8 preset has correct "pre/post" config.
- Cables are okay.
- Volume pedal passes signal.
- If an imported preset shows up empty, it was probably created with firmware that is more recent than loaded on your hardware. Update the firmware!
If you want to make sure you're device is capable of generating sound, try this:
- Add a Synth block.
- Connect it to the grid output.
- Select Sine wave and turn off Tracking.
- This generates a simple test tone.