T4S Tonematch static/distortion sounds

Hi, I've been using my T4S tonematch for a couple years with the same set up, but recently I get a bad static/distortion sound and I can't figure out why.

Inputs-

1- guitar direct in, using Fractal fm3 - xlr cable

2-vocal mic- either dynamic or condenser with phantom power- xlr cable

4- ipad to usb port, to tonematch, to play backing tracks. I've tried different usb cables, DI's, etc.

 

I've swapped out many different cables, mics, phantom power off/on, turned power off/on, and I still can't figure out why it does it. It usually happens when I'm sending all 3 signals at once, for example singing, playing guitar, with the backing track. It sounds like a load static sound, similar to a bad headphone jack being wiggled in the jack, but it's coming through the main output. It's not clipping, and different than a clipping sound. I've tried everything. This particular T4s that I'm using, I bought brand new, less than a year ago. Can you think of any ideas?

 

T4S Tonematch

USA

Firmware Version 1.1.4