Local vs Exp input not showing Gain level

We are using the tape output from a Mackie mixer into the RCA connector (socket 45/56) of our GLD 112. When we select the channel then Processing → Preamp, I don’t see the Gain level shown (just trim). Why would there be a difference between a local input vs Exp input?

I really like the feature of seeing small adjustments to the Gain.

There is no gain, there is no preamp. It’s a (consumer level) line level input so there is no need for a preamp, given that the job of a preamp on a mic input is to boost signals up to line level.

It’s not because it’s a local input, the XLR inputs on the back have preamps on them, and you can adjust the gain of those.

Chris