So these files are pending move?
That's not good. Check the extended drive schedule to verify file moves are scheduled. You should also check your media group to verify you have free space. Let me know if that helps.

Thanks for the reply. The schedule is set for all activities at all times, no restrictions. The media has over 1 TB free. The odd thing here is the pending moves total 276 GB but there is a total of 246 GB of data on the extended drive...

Force a drive scan. This should truncate the existing move lists and rebuild from scratch. You'll see how long it takes in the DX admin under drive scan statistics.
Let me know if that helps.