When crafting with the Runic Altar, if you throw the Livingrock a little too short / far and it misses the altar, but it appears to jump on to it due to (I believe) syncing issues, and you attempt to craft, the components disappear, leaving the Livingrock sitting on top of the altar. No attempts to craft will work after until you break the altar, doing which drops both the altar and the components. See below video for an example.

https://drive.google.com/file/d/0By0Y_l2gnU0hRzNjX3l3b196Uk0/edit?usp=sharing