personally ive only had a nm taken once me and 4 other BLM were manaburning CC and for some reason i dont know why when he droped down from the bridge he went unclaimed for about half a second which was enough for a solo ninja to use violent flourish to take claim luckly not even a minute after that CC charmed the ninja and we nuked his ass into oblivion and took our NM back and killed it . but yes sometimes nms go unlcaimed for reasons i dont know we werent out of range of it and lack of damage wasnt a issue we got it from 100% down to 20% in less than 2 minutes not sure what happened there.