Kerbal Space Program

I believe this was intended. Without access to the Communication (comms) network, a probe has "limited control". The tracking station provides all the telemetry about which all planets and objects are moving. The probe has limited sensor and tracking abilities and cannot calculate new maneuvers nor can it be sure its orders to execute a maneuver have changed. It's limited control allows it to go full thrust in one of the given navigation directions (pro/retrograde, etc.) available to a pilot of the same level, but for fine tune adjustments that require more sensor data and complicated calculations, the probe relies on the tracking station computers for that.

You have to think of Kerbal computing tech like Earth's earlier days when mobile processing power was very limited. The probe follows directions when in comms and we built our probes to continue following those instructions even when comms were broken due to passing around behind planets because we expected to be able to reestablish comms when it came back in view and relay to us its observations about the success of following those instructions. With that data, we can establish new instructions.

There are a couple things I would think that a probe without comms should be able to do. First off, any maneuver that is programmed should be executed on time, and the player taking any action to intervene should indicate that the situation has changed and the maneuver has to be aborted. At that point, it should be deleted automatically and limited control continues as if the probe was making decisions based on its data. Also, in that same sense, the tracking station should have limited data about the probe or the ship during this blackout. Data such as current mass (fuel burning changes this), and Kerbals still alive on board to name a couple. In the absence of any programming to execute the maneuver for us automatically (due to the need for a physics bubble around the vessel), the probe should at least be able to determine that the execution point of the node (half the time needed to burn after the node time) has completely passed and delete the maneuver when we tell it to. This can still prevent us from adding a new maneuver, but if more maneuvers were plotted, we would have to have a consensus on if they should all be deleted as a result of this failed execution, or if they should be followed (or waited for) as well.

So the simple answer is, that because maneuvers can be missed when we forgot to take control of the ship in time, we need to be able to pass instructions for how to handle that, and the lack of comms prevents that, therefor, the probe cannot let the maneuver plot go because it might come back within range after the planet obstruction is removed, or another relay gets closer and therefor, it will need to be able to receive instructions to alter the maneuver before executing it.

It is pretty annoying that you can't delete the node, but the fact is that when you make a mistake, you need to feel a consequence for it. Knowing you will lose comms if you go behind a planet or too far is just one more event you have to plan for and not doing so is a mistake. Often we get to rescue craft that we lost due to such mistakes, and that is all part of the game. If you can't fly without comms, don't lose comms.

Converted to a feature request and changed the subject as appropriate. You may also wish to try changing your difficulty settings to disable "Require Signal for Control". This will do more than enable deleting the maneuver node but it might be what you would use if you didn't agree with the node control features by default. This setting is in a game, under Settings, Difficulty Options, Advanced.

Clearly not agreed, so withdrawn.