o maybe the first test is to get loopback connection between the two ports of the product and see that there is a link on the external port, maybe then we can do some test to pass traffic from one port and get it on the other.
Then probably have two system installed with the product and make direct connection between them without the BlackDiamond-X8 and see link and traffic.
And then get the BlackDiamond-X8 in between and see if there is any problem.
Can you tell why you are using LR4 and not SR4? Is it a requirement? The cost of such transceiver is much higher than SR4.