Discredited report about an eruption in 2008
A report from the Darwin Volcanic Ash Advisory Centre in August 2008 reports a pilot observing an ash cloud from Sumbing volcano. No other confirmation about activity at Sumbing has been known from ground observation or other remote sensing, which is why it is believed that there actually was no eruption from Sumbing. A possibility could be that the "volcanic ash cloud" from Sumbing was a could of dust or smoke caused by bush fires etc, or if it was a volcanic ash cloud, that it came from a different volcano.