unable update unit price in sale order for production , but same item in test database, can update

The issue of being unable to update the unit price of line 2.1 in the same sales order while being able to update the unit price of line 1 .1, 1.2 for production database

but same item in test database line 2.1 we can update unit price. how to check this case on production? please advise , how to change setup item  L8000001 to allow update unit price after booking order status.