Hi Shale @CookiePuss,
Could you add a screenshot of your shelves with the material tab open? That makes it easier to narrow down the problem. Without seeing what’s going on it’s pretty hard to pin point the problem.
The assign button is only available in edit mode. It enables you to assign different material to specific parts of a mesh. So that’s correct behaviour.
In object mode you can only add materials to the whole model and add more material slots which you can then assign in edit mode.
