I am running a library server where users are able to upload speeches (with validation) and also attach images as the thumbnail for them. However, it appears when attempting to edit these images, they are given with a screen: 

An error has occurred
“marko1” does not have access to this category.

in  Home→ Content Management→ Galleries→ An error has occurred

However, for global permissions, all super members have **every** permission to upload, and edit.