Thank you very much for the workaround!
For anyone else with this issue, if your existing cache drive filesystem is different than what you want the new drive to be, make note of your existing filesystem before starting. Then after assigning your new drive to the cache, go into the properties to select the filesystem you want (make sure cache slots are set to 1 to allow changing the filesystem). After formatting and assigning your original cache drive back, you will need to go into its properties and re-select your previous filesystem.