Just chiming in on this old thread to say I had the same exact issue (these exact 4 cabs oddly giving no output) and the firmware reinstall fixed it. Because I already had the latest firmware, I couldn't figure out how to reinstall so needed to hunt down how to do that myself. For anyone needing to know... I downloaded Line 6 Central, and separately downloaded the latest firmware for the HX Stomp from Line 6. Then in Line 6 Central I did "Update/Install from File," selected the one I just downloaded, waited, and woo hoo, everything works again!
