Expected:
(HR.EMPLOYEES, as seen on SQL Developer Classic 23.1.1)

Got:
(HR.EMPLOYEES, as seen on SQL Developer Classic 26.2.0)

Accordingly, the table Properties dialog (*) does not show any column on SQL Dev 26.2.0, whereas columns are shown as expected on SQL Dev 23.1.1.
(*) Select a table, click on the right mouse button, then select Properties in the context menu.
This makes the model tab on table editors useless in version 26.2.0.
Regards,