Just looking at our seler dashboards too...

I see our return rate is suddenly 0.05%.

Says one return out of 1,827 but we have never had a return case and if I filter back for the past 18-months on returns there are none showing as there have been none.

So I don't know what they are up to. Looks like false defects to me.

On our other store the return rate is 0% as it should be.

Possibly a phone call to them in your case to have it corrected but in our case it is not affecting our ratings so probably will not bother until/if it does.