When I add .png file for the 1.12.2 bibliocraft in the custom paintings file where you add your own paintings to use in game. this happens

[LittleLightz]

Hi,
When I add .png file for the 1.12.2 bibliocraft in the custom paintings file where you add you rown paintings to use in game. this happens. It does not load all the pictures, but the pictures are all .png file. It shows some but not all, any suggestions on what I can do? (I'm using curse forge too)

Please help, IDK what to do....