DNAT Rule Not Working with Additional Static IPs

I'm having an issue with forwarding RDP from an additional public IP address assigned to an internal server. I've added the IPs to the eth0 interface, the firewall has port 3389 open and DNAT does work for the primary IP of xx.xx.xx.244 to the internal 10.0.1.10 but the additional IP xx.xx.xx.243 isn't connecting to 10.0.1.11. My redacted config is attached.

I should add that I've set up similar configs using PPPoE Internet connections without a hitch ... this one is a cable connection (via Rogers) with a /29 static IP block and perhaps I have to do something differently?

Thanks in advance for your help!

M.