DIAGNOSIS Yeah, this one's common. The drip tray is shallow, and if the grill isn't perfectly level (or tilted slightly forward), grease will run off the plates and miss the tray entirely, dripping down the front. Also, fat can sometimes channel in unexpected ways on the sloped plates.
FIX First, always ensure the grill is on a perfectly level surface. Second, when you place the drip tray, make sure it's pushed all the way in until it clicks or stops. During cooking, keep an eye on it and empty it more frequently than you think you need to—it fills up fast.
IF THAT DIDN'T WORK Check the slope of the grill plates themselves. On some units, the front edge might be bent slightly upward from handling, directing grease away from the tray. Gently bend it back down if you can, but be careful not to crack the coating.
HEADS UP Never let the drip tray overfill to the point where grease touches the hot base of the grill. It can smoke heavily or even ignite. If you're cooking something very fatty like bacon, consider placing a foil-lined baking sheet under the front of the grill as a backup catchment.