What would cause the gutter underneath Vented Drip Edge to fill up with ice?

Check these things if the gutter underneath Vented Drip Edge is filling up with ice.

If a gutter installed 2 inches below the Vented Drip Edge is filling up with ice to the point the ice is reaching the intake vent portion of the product it is possible the that is not draining properly. This could be from debris or from the gutter drain freezing.