Hi,
here is winbox proxy-arp setup:

Are these interfaces in some slave/master relationship? Do you have bridge setup?

Are you using winbox or CLI? Also, can you export config( hide sensitive).

Hi,

try to set proxy arp on both interfaces. That should do the trick ( considering you do not have any firewall rules in forward chain which could deny communication between subnets).

u need to accept in forward chain communication between that 2 subnet