DIAGNOSIS The machine is either in a too-warm environment or the water you're using is too warm to begin with, so it can't get cold enough to form a solid cube in the cycle time.
FIX First, always start with cold tap water or refrigerated water—never use warm or room-temp water. Second, make sure the machine isn't next to an oven, in direct sunlight, or in a room hotter than about 90°F. The compressor needs a reasonably cool ambient air intake to work properly. Give it a few inches of clearance on all sides, especially the back vent.
IF THAT DIDN'T WORK If you're using cold water in a cool room and it's still happening, the refrigerant charge might be low or there's an issue with the cooling system. That's a repair job.
HEADS UP The "9 cubes in 6 minutes" claim is for the first batch under ideal conditions. Subsequent batches take longer because the unit has to cool down again, and the ice will be less solid if you're running it continuously.