Check if your plan has any collisions. You can check collisions on your plan by looking at your placed objects in the Plan window in Furnishing mode.
Units should feature clean, unbroken lines when placed correctly next to each other. If they have collided, there will be dotted lines where the objects have crossed paths.
In this example, the unit has collided with the filler to the left.
- Move your unit by clicking on the unit.
- Click and hold the corner of the unit next to the filler and drag to snap it to the filler. Your cursor will appear as the snapping point symbol:
This indicates that you can release the mouse button.
The plan now shows one clean line, and the plinth should return.
Should this be not the case, try enabling the plinth per unit manually:
- Right click on the unit and select Properties at the bottom of the list.
- Locate Plinth in the list on the right-hand side and click on it.
- Using the drop-down box at the bottom of the window change the option to On.