I recently had an FUE hair transplant along with PRP. Its been 3 weeks now and my donor area is healing nicely apart from this particular patch.
This appears to be shock loss causing loss of the hairs in the donor area. I am assuming that the surgeon took out too many grafts too closely in that area which impacted the circulation to the donor area. We have performed a thousands of FUE sessions and have never seen this complication. You should wait it out and possibly in 4-7 months the some of the hair will return