I traded in all of my blood shards and then upgraded the items into legendaries, but one would not upgrade. When I asked general chat they said the item wasn’t level 70 and that it shouldn’t be possible for kadala to give lower than 70 items on a level 70 character. (I have one character this season. level 70 para 1194 at this time.)
I’ve never seen it either, so the possibility never even occurred to me. It’s not a major bug, but I thought I’d report it nonetheless since it’s so weird.