I have a 3TB external drive that I've been using for backup and general storage, and decided to make a new partition on it to keep the two things separated better. Using Windows' Disk Management tool I tried to shrink the volume by 775GB, but ended up with two new slots of unallocated space, one was about 28GB and the other is 746GB. I was able to create a new volume using the 28GB, but deleted it since it wasn't enough and extended the primary partition using that space. HOWEVER, the larger block of unallocated space I can't seem to be able to do anything with. As you can see in the screens, everything is grey'd out.
Do I need to reformat the whole drive to be able to use this space again?