Invisible bards are starting to multiply, and some are very persistent. My friend has one haunting her Exorcised Coven Cottage. I hear one near my Twin Arches property regularly now. They crop up right next to wayshrines, they crop up in the entrances to dungeons and delves, they will pop in to sing clashing and competing songs in a tavern where there's already a bard singing (this is particularly horrific to hear). In one particularly weird instance, one of them possessed my friend's twilight matriarch while we were doing a dungeon and once I realized the sound was coming FROM the twilight, my friend dismissed and resummoned her and that got rid of the bard possession. But it's really kind of getting to be a very common bug now, and shows up in so many circumstances with so many variables that it's kind of impossible to pinpoint any common thread. It has definitely gotten a lot worse lately, though.