I think some might have hedged their long KC positions on RC (long arb). Rising certs and selling ahead of VN farmers might also be a reason.
But when one looks at Conilon differentials, Robusta certs will start likely start to drop very soon. And Tet is coming in Vietnam. I think the spec shorts will be forced to cover.

Also if you look at the exports from the ICO, you can see that it really ain't good.