I guess the Joint Lebeling is wrong now:
Right-side joints are labeled as Left.
I think fixing that would help with dealing with Mirroring Skin Weights issues, when first two methods for Influence Association don't give satisfying results, e.g. when the joints are at the same place.
Also it's impossible to change the right-side joints' Joint Labelling side from "Left" to "Right". It's not the case with Centre- and Left-side joints: Side can be changed to whatever value. It's like the right-side joints' labelling is locked/connected.