I think Andreas is on the money here.
Each Mono->Stereo crosspoint has a pan control. Each Stereo->Stereo crosspoint has a balance control. In the case of a linked mono pair to stereo crosspoint, there are two pan controls which are inversely linked, effectively giving you a ‘width’ control. As Andreas mentioned, each stereo mix will provide each of its sources an independent pan or balance control as appropriate. The exception being groups, which are designed to follow LR.
Select your stereo mix on the ‘Mix’ keys, select the left side of your source on the ‘Sel’ keys, then turn the Pan control on the superstrip all the way to the left. This should not affect the pan on your LR mix.
Output balance is something entirely different.
DC