While launching MRP, snapshot delete worker fails

While launching MRP, the Snapshot Delete Worker fails with the below error ::

SQL Error Code: -1502

APP-FND-01564: ORACLE error 1502 in mrnwpl_delete_mrp_table

Cause: mrnwpl_delete_mrp_table failed due to ORA-01502: index 'MRP.MRP_SYSTEM_ITEMS_U1' or partition of such index is in unusable state

.

The SQL statement being executed at the time of the error was: DELETE FROM mrp_system_items

WHERE compile_designator=:vdesig

AND 1=1

I have checked the note  ::  Error ORA-1502: Index '<SCHEMA_NAME>.<INDEX_NAME>' Or Partition Of Such Index Is In Unusable State (Doc ID 756324.1)

Customer is recreating the indexes, but everytime they cannot do this as this is a time taking process.