Question

Why is an order, which is plannable (status = plannable), shown greyed out (read only) in the trip planning

Answer
 

Therefore exist different reasons, for example, the taskfield was loaded in that planning with the option “show only”. Or one action (Pickup / Delivery) of that order could not be handled in the chosen time period of the trip planning.

You can get more information about the reason in the field “object information”.