Disappearing Drawing Substitutions

Hey everyone. Ive been trying to create a cut out character rig and have been running into the problem with my drawing substitutions disappearing. This happens once I close out of the program and open it up again. I can re-add the drawings no problem but in my library I can see that its adding more drawings on top of the “vanished” ones. It reads that my old drawings were there but its not showing when I change to them. Other parts of my characters body shows up but its just certain limbs that keep needing to get re-added.

Am I doing something wrong? Are files getting mixed up? This bug is really annoying and frustrating. Please help