stats --system output reports a Current Bytes value smaller than the Post Dedupe Bytes and/or the Post Compression Bytes, the reported values are incorrect.
maintenance --filesystem --start_scan
The filesystem scan will check the actual bytes on the system and will fix the statistics.
If the statistics are still incorrect after the scan and your system has an OS version prior to 4.0.3, perform a cold reboot and upgrade your appliance.
Once the upgrade has completed, run again the filesystem scan.