Sorry about the left motor power set at 50% all I can think is because I use a beta version of the software when I set yours up it changed it to 50%. Anyway you sorted it programming error not a fault.
Reflashing the firmware doesn’t effect the sounds or settings on the IBU3, sometimes with new features added a factory reset is best to make sure no incompatibility issues between old settings and new features/settings. We will advise when this is the case.
Regarding the no main gun sound, this is because in airsoft mode the IBU3 is waiting for the signal from the microswitch on the back of the airsoft to trigger the sound and track recoil if activated. On the current hardware version of the IBU3 you need to plug it in as per this picture
The next production batch of IBU3 will have an updated PCB so it plugs into the xenon flash sock just like the Heng Long & Taigen systems. Again we will advice users when the revised PCB is sold.
Ian.