Di2 front derailleur calibration is set by the amount of travel allowed between the limit screws, so just setting the high limit farther to the outside should fix it. Just keep moving it until the chain hits the big ring consistently from all rear combinations. Of course, make sure the outer plate is parallel to the rings and no more than1-2 mm clear of the tallest teeth on the big ring. I like 1-1.5 mm. Also, make sure the chain isn't worn out.