Plywood sheathing rotten at drip edge of roof

I have a 6 year old barn style workshop 2 story 36'wide x 50' long with 25' wide enclosed sheds on both sides. Sheds are 3/12 pitch with 5/8 sheathing,Titanum underpayment and metal roofing. Screws are on the flat surface. Foam enclosure strips at lower drip edge, at pitch breaks and at ridge vents. Screws started to come loose at drip edge of shed roofs. I raised up the metal and found sheathing rotten 6 to 8 inches above foam enclosure strips. Can this be caused by condensation.