Superacids

I have a G50, it's worked flawlessly for months. But it just started having a problem. Reception is great, full green bars, new batteries. But now it only works if I play hard. It will no longer pick up soft playing. It's like there is a gate effect on it. I tried two guitars, it's not the guitar output or pickups. It's definitely the g50. What could cause it to only transmit loud playing and not pick up soft playing despite having a great signal (tried other channels all are the same). Thanks