I'm trying to do the same thing but am not having any success. I am logged in the database, and have navigated to the ost_ticket_priority table.
It has the following:
priority_id
priority
priority_desc
priority_color
priority_urgency
ispublic
I went ahead and created a row below ispublic called "test_priority"
Not sure what I am missing here, any insight would be really helpful.