On at least some Windows 11 installations there is no visible difference between a ticked and an unticked CheckboxMenuItem with Look and Feel "Windows" if the item is associated with an icon. This applies to nearly all menu items of the "View" menu and at least to two of the "Preferences" menu items.
This seems to be rather a problem between Windows 11 and Swing, apparently. The strange thing is, however, that no similar report can be found across the net. Maybe few develeopers make use of the opportunity to equip a CheckboxMenuItem with a symbol.
Workaround in this case: Choose a different Look and Feel.