We have handled your problem through the Support channel.
For other readers' reference: NLS_DMU_USAGE is a statistical parameter for the database feature tracking functionality. It is added by the DMU and it is not supposed to be ever deleted from the data dictionary. It should not cause any issues except for applications that provide a too small buffer to select the NLS_DMU_USAGE value through SYS.PROPS$. This value may be as large as 4000 bytes, as the definition of the SYS.PROPS$.VALUE$ column says.