Content library Textures section is missing the HDR environment textures. The env. textures appear after manually deleting the TextureBundleIcons folder (e.g. on windows C:\Users\mabadri\Documents\QtDesignStudio\bundles\TextureBundleIcons)

This happens because the env. textures were moved under Textures section a while ago, but QDS current doesn't have any versioning, change detection for textures to detect this change and redownload the textures.