How do you set the value of mtl_item_catalog_groups_b.item_creation_allowed_flag?

On the Item Master screen, when I query a given item and try to modify any data field and save it, I get this error message:

APP-FND-01048: Use of this combination restricted by WHERE clause ' (  ITEM_CATALOG_GROUP_ID IN  (SELECT ICG.ITEM_CATALOG_GROUP_ID          

FROM MTL_ITEM_CATALOG_GROUPS_B ICG                              

WHERE ICG.ITEM_CREATION_ALLOWED_FLAG = 'Y'                              

AND ((INACTIVE_DATE IS NULL) OR ((TRUNC(INACTIVE_DATE) > TRUNC(SYSDATE))          

OR (:MTL_SYSTEM_ITEMS.ITEM_CATALOG_GROUP_ID=ITEM_CATALOG_GROUP_ID)))) )  '.

I've found the record in the mtl_item_cataglog_groups_b table for this item, and the item_creation_allowed_flag is set to 'N', so it's clear why this statement is failing.