Issue

When Samsung Galaxy S4 is connected to a Windows PC, DCIM\Camera folder appears to be empty. But when browsing on the actual phone with an Android File Manager (or via Gallery app) you can see that there are hundreds of images in that folder.

Resolution

Issue was resolved by changing USB PC connection option on Samsung Galaxy S4 from Camera (PTP) to Media Device (MTP).

This option can be quickly accessed via Android notification panel when a USB cable is connected to a PC.