2tbs unavailable on my 4tb hard drive

I have a 4tb 3.5 wd hard drive that only shows that 2tbs are available. Depending upon the file system I uses on it sometimes disk utility will show a 2tb free space partition that is the missing space but it aways fails to remove the partition. Is there away to restore the missing space?

I caused the problem by cloning a 2tb 3.5 Wd hard drive to the 4tb hard drive using a 2 bay cable maters cloning dock.

This is where I got the dock:http://a.co/d/fwBQZN6