There haven't been any updates on the health of the Crown Princess for quite a while. There were some engagements last winter and a State Banquet Mette-Marit was unable to attend that the Court stated due to health problem or needing to rest. Mette-Marit said once that she has to take each day on as how she's feeling that day.
I take it back there were a couple of engagements in recent weeks that MM was unable to attend so Haakon took them on.