Aw, I figured it out! I stopped the array, clicked on each disk, change the disk to xfs for the filesystem, and then restarted the array. Then I clicked on the format option, and BAM... formatting began. As a note to others (if anyone else has similar problems), you must change the filesystem under drive options (accessible by click on the drive) and change the preferred filesystem. Prior to changing the filesystem by clicking on each disk, it always showed as ext4 and would not format, however it is now formatting.