Perhaps this has something to do with: 0003243 where loot briefly returns to the original location you picked it up from before appearing where you dropped it.

Same here, happened on the hospital ladder on the hospital across from the school in the area with the many high rise apartment buildings above cherno

I found that when you have the bipod and bayonet attached to the mosin and you carry it on your back, panning the camera around in 3rd person view causes those attachments to flicker and dissapear.