So I'm trying to mirror the weighted half of the model to the other half, but the mirror mode is being an asshole. Added all the bones in the list, checked vertices, selected all of them, went to mirror mode and... pressed green to blue bones. No dice. Green to blue verts then. Nope. It won't transfer the weights. What do…
Adjust the the mirror plane, mirror offset and mirror threshold. If your mesh isn't symmetrical it really won't work that well. Sometimes the mirror plane is way off to one side, it should be in the center where you'll see little circles or boxes. When you get it in the right spot things should light up like a Christmas…