If I create a new detail, select it, lock it via the properties window, then double click into the detail, with nothing selected look at properties. Over here, the locked check mark does not show. While the detail is active, I can toggle its locked state by clicking on the Locked check mark, and the locked state will sometimes change, but the check is not drawn. Double click out of the detail, select it, and properties will correctly show its locked state.
I have seen the opposite, where the detail was unlocked, but when the detail was made active it showed locked, but I haven’t been able to reliably reproduce that.