Linked Channels Will Set To Pre Fader In Aux Mixes
Link 2 channels and you may find the second (even) channel of the pair sending to aux mixes as pre fader.
This has been observed on Si Performer, Si Expression firmware v1.8 Build 006 and 1.8 Build 0012, as well as Si Impact firmware v2.0 Build 0006 and v2.0 Build 0012
Intermittently, when you link two channels (odd to even pair), the second channel (even) will send signal to an aux mix set as post fader, even with fader down. In other words, that channel will be set to pre fader into its aux mixes. But the Faderglow color will still be green, making it look as if it is still set to post fader. It seems to be more prevalent in Stereo aux mixes, available from mix 9 thru 14.
Here, you see the mix set too all post fader, indicated by Faderglow color of green.
Then you link 2 channels together. The channel's Faderglow will show as white to indicate 2 channels linked.
You will notice Faderglow still shows all channels as post fader.
If you run into this issue, here's how to resolve. Select that channel and Select Input on screen. Scroll down to the affected mix in the Per Mix Post/Pre section. Scroll to All Pre Dyn and select by pushing down on encoder.
Then set it back to All Post Fader.

Operation will then return to being Post Fader on that channel to that aux mix, returning to normal..