I was arrested today in the Goblin Camp and have the same bug, only that I had the Mysterious Artifact in my possession before. I had jumped over the destroyed bridge near the Githyanki in the northwest, you then land above the Goblin Camp. Shortly thereafter the cutscene was triggered, where I was entrusted with the Mysterious Artifact.
Resting at Camp or dropping the Artifact from the evidence chest onto the ground so that it lands in my inventory again does absolutely nothing... The Artifact remains in the chest...
By the way, Shadowheart should no longer have any animations showing her desperately trying to open the Artifact, since it had been out of her possession for a while when the artifact came into our possession....