"lsdg" command displays minus in Usable_file_MB column

Hello, experts.

Environment:

ODA X7-2-HA.

RDBMS version:

     [oracle@oda-x72-node0 ~]$ /u01/app/oracle/product/11.2.0.4/dbhome_1/OPatch/opatch lspatches

     22502549;OCW Patch Set Update : 11.2.0.4.160419 (22502549)

     22502456;Database Patch Set Update : 11.2.0.4.160419 (22502456)

GI version:

     [grid@oda-x72-node0 ~]$ /u01/app/12.2.0.1/grid/OPatch/opatch lspatches

     26260804;Support Scan IPs variable value through the command line arguments

     28140658;

     26559661;Support skipping post install CVU checks.

     28016681;ACFS Interim patch for 28016681

     27674384;Database Apr 2018 Release Update : 12.2.0.1.180417 (27674384)

     27464465;OCW APR 2018 RELEASE UPDATE 12.2.0.1.0(180129) (27464465)

     27144050;Tomcat Release Update 12.2.0.1.0(ID:171023.0830) (27144050)

     26839277;DBWLM RELEASE UPDATE 12.2.0.1.0(ID:170913) (26839277)

Using ACFS for 11.2.0.4 database files.

Question:

Don't understand why "lsdg" command displays minus in Usable_file_MB column. At file system level "df -h" displays 24TB as available, directory contain only 12TB of data: