UMC 1820 line outs and LOGIC PRO

I'm using a Behringer UMC 1820

I have a few outboard units that I wish to use as inserts using the I/O tool in Logic Pro.

However, not all of my line out channels seem to be functioning properly and I think it has to do with Logic's Surround settings. Some line outs have a lower level and some don't even send out any signal.

No channel is set to surround however and I don't really know how to fix this issue.

Does anyone have any tips?