Getting "Storage space running out" message in Galaxy S4; *#9900# does not show any menu
Approach 1:
Many users have had the problem of &quot;6GB of miscellaneous files&quot;. The problem might be because of /sdcard0/DCIM/.thumbnails.
You can go ahead and delete the folder. This may free up your memory. To delete .thumbnails folder, you need a file manager that can see hidden files. After deleting the folder, also delete LOST.DIR and reboot. Clearing apps' cache is recommended.
Approach 2:
This might be a Verizon carrier bloatware. Verizon customer support seems to confirm it (see reply #5 in this link). This problem is not just confined to Galaxy S4, but to other phones too (Note 2, Note 3 Galaxy S3 S4 S5).
Deleting  /data/media entirely seems to have worked for some (needs root access).
Alternatively, installing a custom recovery (eg: CWM) and choosing to delete all backups in the Internal SD seems to have solved the problem for many users.