Ah I think this may be down to the filter algorithm. Are you using the more extreme dB filters - the 100dB parametric and the high and low shelves? The maths can go a bit wrong if pushed too far with these ones. Not yet found a solution, I think it may be to do with the 8-bit calculations of the floating point algorithms. I won't go into any more detail before confirming we're talking about the same thing. Next time it happens, goto filter type and switch up and down a value and let me know if sound comes back. thanks!