Unexpected behavior in structure.GetAssignedHU()

[ctannell]

When the structure has "Assign CT value" selected, the HU is properly returned by the API.

However, when the checkbox is not selected, it will still return a HU value. That value is zero if the structure has never had the value set, or it will return the value that was last set. I don't know where it gets this value, as the MaterialCTValue column of the Structures table in the DB is null or empty when the assign CT value box is not checked. This seems to be a bug to me.

Edit: I'm using version 15.