There is an inconsistency in logging traffic from Internal networks connected to the LAN# interfaces and LAN#.## VLANs of SMB appliances.
On my 1550 R80.20.05 (992001208), with two networks defined, 10.x.x.x on LAN1 and 192.x.x.x on LAN2.10, Global NAT for Internal Networks enabled:
NAT is actually working fine, but the logs are all over the place:
Also, in the Security Logs List view, we can see the Interfaces:
But in Log Details, this data is absent.
Additionally, there is no way that I see to define the Network as "Internal":