What have I done here? See the Screenshot. I can see the Clarinet 1 and Clarinet 2 parts in the score and in the Player panel but they are not appearing on the right side in the Layout panel or in the drop down menu under Full Score so I can’t actually see those two parts. I know I have done something wrong but can’t seem to think it through.
Select the empty player on the right side and check Clarinet 1 on the left side.
Create a new (part) layout (or duplicate the new Clarinet 1) and assign Clarinet 2.
You can reorder the layouts by dragging and I recommend also to renumber the layouts (via the context menu)