@kkashyyyk, thanks for reaching out. What you're experiencing is wiring issue -- most likely a wire is crossed, or you might have a bad solenoid that is causing the Iro to go offline.
Since you know it happens when one of 2 zones attempt to run, you can easily troubleshoot this by removing one of the two wires to see if the issue continues. Once you know which zone is causing the feedback, we can troubleshoot further. Do you happen to know if these two zones share a common wire separate from the other 2 zones that are working correctly?
Feel free to post a photo of your wiring here and/or email one to our support team (email@example.com) to review.