I know it doesn't specifically state it in the current FW notes, but AX8 input gain was definitely affected by the FW. My main two guitars an Ibanez Jem with Evo's required a pad of 6db/almost 12db as did my EMG 66/81 axe...now I barely get the red with it down to zero.
Running your wireless lower than wide open will almost certainly reduce your signal strength.Would running wireless into the input vs. direct cable potentially be the cause of this?
You can adjust the input pad.
On the unit press shift - setup, and then go to the I/O menu. There you can adjust the input pad. The default is 6 dB. If you reduce it to 0 dB, you should be getting more LED response and a slightly better signal to noise ratio.