Weapons don't attach to hands of Playermodels with custom animations

[GreenGhost21]

When using playermodels with custom animations (such as those made by Echo), ArcCW weapons end up at the playermodel's origin, rather than in the hands of the playermodel (despite said playermodel having ValveBiped.Bip01_L/R_Hand bones).

I talked to people in the DIamond Doves Discord server about it, and we could not figure out why this was the case.

Maybe someone here might have some insight as to why this happens (ideally with a potential fix)?

[TheOnly8Z]

Can you specify which weapons and which playermodels is causing this issue? A lot (but not all) ArcCW weapons use MirrorVMWM which should be set to the R_Hand bone.