Multiple people have been reporting a battery life problem with the IKEA devices that just started happening about a month ago when the Zigbee stack was updated. There are several discussion threads in the forum about it. I should note that this has also been reported with a couple of other brands of hubs, but I don’t know the details.
It does appear that the devices are responding with a long poll instead of a short poll, so essentially they are never going to sleep and they are going through batteries in just a few days.