What happened was you started a preclear, then paused it either manually or by stopping the array. When the array started again, the preclear operation was resumed incorrectly even though the disk was moved to the array. I've reworked the logic for pausing and resuming preclears so a preclear won't resume on a disk that is not a unassigned - i.e not in the array or a pool, and the pause status more accurately reflects the actual paused status of the disk.
As for the Historical devices, wait until the remove 'X' turns red so it can be removed. That may not happen until the next reboot. It's harmless as it only indicates that the disk was at some point seen by UD.
I will be updating UD preclear and you'll want to upgrade so a preclear cannot resume again.