I don't know when the icing started I'm afraid. The LTI (low turbulence inlet) is directly above the cockpit. The particular thingy isn't used for cloud work, it had just been left fitted.
However, you're right, loss of data due to icing is a big headache. Most instrumentats we can and do de-ice, but a few can be a real headache. The worst is a turbulence probe on the radome - electrical heating would interfere with the radar and chemical de-icing would muck up the chemistry instruments behind it. We do often lose data from that one.
G