Since sometimes IPT generates unexpected translation entities in database,
IPT does not work properly in certain case.

If database includes any null value on [Key] or [Translation],
IPT works for translated messages but it does NOT accept new translation anymore.

When enabling IPT, it should clean up database by using following SQL.
DELETE FROM AO_xxxxx_TRANSLATION_ENTITY WHERE [Key] is NULL or [Translation] is NULL

Or, at least it needs shortcut tab from configuration tab or administration page.

Thank you.