Noise despite offsets

[JoeJack]

I'm new at running EEG, so forgive me if this is a non-issue. We ran a participant and had a lot of noise despite acceptable offsets (<40).

I know this isn't the result of the CMS/DRL cord or connection (I did the "salt test" and we have a backup cable). It doesn't appear to be individual electrodes either - this is a brand new set. I've also changed out the optical cord.

Any idea what this may be (or if this is an issue at all)?