Hi,
mc 1.12.2
forge 14.23.5.2838
i've encountered this problem running with robotics parts 0.2.10.16

when you get a robotic arm (left or right) with this mod, backpacks becomes invisible but are still usable perfectly

traveler backpack version: 1.0.19.19
same problem occurs with galacticraft 4.0.2.211: air tank on back invisible but works
and backpack 3.0.2 too, back pack are invisible

Duplicate of #16 Players models are generally incompatible