The rejection of the statement is by design. The distribution of the network which includes the failover IP addresses is not supported.
Use a more specific network within the EIGRP statement to exclude the failover network from dynamic distribution.
You can try to remove the failover command (where the IP address is included) and add the 0.0.0.0 statement in EIGRP, once the command is added you can try to reapply the failover command. I haven’t try that before so I am not sure if that's going to work.
The real solution will be to be more specific on the EIGRP statement.