Also wanted to add this as it helped for my situation although i wouldn't consider it an acceptable workaround.
I decided to move my movie collection from my array of two spinning disks to my cache pool of two SSDs.
I changed the shares>cache setting from Yes to Prefer for the movies share then invoked the mover.
If you then click on the shares>view button on the far right side of the shame name you can sort by location and watch the progress of the folders being move from "Disk1 " to "Disk1, Cache" then finally to "Cache".
Obviously your names for the array and cache may differ.
Unfortunately this doesn't auto-refresh but hitting the refresh hotkey/button on your browser (or at least with firefox) does update the current status.