The confiscation of the Southern Slaves had occurred before the 13th Amendment was passed. So 13th Amendment would have been an Expost Facto Law. So the federal government would still have been responcible for the payment for siezed property under the 4th Amendment until the 13th Amendment was ratified by the states. But not afterwards for the slaves freed under the 13th Amendment in the Northern and Border states.
Under the Constitution no law can be retroactive to cover acts committed before it was enacted.