Hi,
mc 1.12.2
forge 14.23.5.2838
mod version: 1.0.19.19
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

this is just an issue with cyberware not playing nice with other mods and completely changing the player model. i personally recommend setting "Enable changes to player model (missing skin, missing limbs, Cybernetic limbs)" to false in the cyberware config because of this.