Hello! I know this post is a while old, but others may experience the same issue.
I have an XG125 appliance and had the same problem.
How did I solve it?
The appliance has 8 ports, and pfSense detects them all, but the ports are reversed in relation to the silkscreen numbers.
Here is a list of ports:
ibg0 = port 5
ibg1 = port 6
ibg2 = port 7
ibg3 = port 8
ibg4 = port 1
ibg5 = port 2
ibg6 = port 3
ibg7 = port 4