As I mentioned in the original post, the selected folder is neither on a network location nor on a removeable location. The selected folder is on a local drive, in my home folder, with full read/write permissions.
On a _different_ computer, the relocation works as expected. The only difference I can think of between the faulting computer and the successful one, is that the faulting computer's home is a zfs volume whereas the successful computer's home is ext4...