Woah, lots of people attacking my question and not answering it ( Except Mike, thanks Mike I emailed them as soon as I saw your reply. ). Don't mean to be unappreciative, I bet there's lots of inexperienced asking these types of questions. For reference I'm an Electrical Engineer so I'm not your average enthusiast.
I'm using a Sunny Island 6048 to charge. I'd hope a $5k MSRP inverter has a good idea of the current leaving it, and my expensive and calibrated clamp meter agrees with it exactly, only the batrium is off. And it's only off on charge, on discharge they all agree.
AND the result is my SoC is constantly shifting down quickly and having to be reset on discharge (because it under-tracks energy going in but correctly tracks energy going out.)
I've made sure there's no possible explanation for current flow other than a mis-calibrated or defective shunt. Even disconnected my DC solar charge controller to make sure it wasn't trying to sink 500W magically somehow. Batrium requested detailed design of my system and their telelmetry logs which i sent them to review. Waiting back to hear what they say.
I agree its odd for a shunt to be inaccurate, and only in one direction. But I'm staring at one that is, I can't explain it. And I don't want to open it up till Batrium decides to cover this as a DoA and replace it. Someone on facebook said loose screws between the shunt PCB and the shunt itself could cause this, but I don't want to open it up till I hear from Batrium.