On the System Info page, which you can access by choosing Configuration > System Info from the Admin main menu, the Filestore usage info seems to be incorrect.
This is a known issue. Similar information can however be obtained from the Troubleshooting Tool, which was introduced with WebCenter 12.1.2.
This is a known issue, which will be addressed in later versions of WebCenter.
If you are using WebCenter 12.1.2 or newer, follow these steps to see the FileStore usage info:
Note: This is an anonymous survey. If you need help from Esko Support, register a Support Case here.