My personal experience based on pulling apart bad grafts over the years is there is usually no callous on the failures. This year there was zero on all my failures. On apples I recall in the past some that had callous but failed, more often than not they got knocked by something.
That is outrageous. It takes me 10 minutes to graft one limb!
Thanks! Thats very helpful!
Yes air exposure causes graft failure and if tbudding remember the “buds should not be added when the air temperature exceeds 90°F. Second, buds should be inserted on the cooler north or east sides of stems.” https://content.ces.ncsu.edu/grafting-and-budding-nursery-crop-plants-
Hard to be sure from a photo but the parafilm looks a bit loose. Perhaps the seal was not airtight.
Maybe try wrapping the whole scion with parafilm to conserve moisture and prevent desiccation? Our weather has been crazy around here, hot/cold/hot, which is probably making my grafts sad too.