XG v18.5: MTA mode and alias IP addresses

My specific problem now is I can't get the MTA mode and alias IP addresses to work. Tried following the instructions in   and https://community.sophos.com/sophos-xg-firewall/f/recommended-reads/122602/sophos-xg-how-to-setup-mta-mode-when-you-have-multiple-wan-ports-or-alias-ip-addresses and I also followed the hint with the Alias IP in "Translated Source" and the recommendation "D-Wan can't be used for routing traffic through alias addresses!! It's only used if you have multiple uplinks/providers!" in the description RE: XG v18.05: MTA mode and alias IP addresses 

Can anyone please help me?

But it is not working.

NAT rule

Edited TAGs
[edited by: emmosophos at 5:45 PM (GMT -7) on 20 Mar 2023]