Cover image series and categories do not appear in OMP 3.1.2-1

I have installed OMP 3.1.2-1. It works fine minus a few bugs that are already reported. However, I am not able to add a cover image to a series or a category. The image is successfully uploaded. OMP generates a cover image and a thumbnail in the designated folder. But it doesn’t appear in the front end and not in the back end. Cover images of monographs are doing fine. For this reason, I don’t think it is an access issue. Any ideas how to resolve this?