hm, just tested it with a new address and seed.
Do you have an existing wallet seed you want to use? (n/no/y/yes) [no]: yes
Enter existing wallet seed: 8894acfbb37f0380ba01787ac6228bb44863f79e1fc5d159486c46c62daa753b
Input error: unidentifiable word 8894acfbb37f0380ba01787ac6228bb44863f79e1fc5d159486c46c62daa753b
Invalid seed specified. Must be a hexadecimal value that is at least 128 bits and at most 512 bits
seems not to work, but i am no expert
if am not counting wrong it is 64characters, so 512bit