When I press arrow top or down the cursor jump not to the same beat. When I will add a articulation at the same beat it would be fine as the cursor jumps to the same beat. See GIF for explanation.
I’ve noticed this issue as well, although when moving between multiple voices on a single stave.
I believe this is because Dorico will always select the closest object when using the arrow keys, (and in your example the bottom of the eighth rest is closer than the note you want selected). Even though this may be useful under certain circumstances, I think it would be invaluable if Dorico could allow a user to switch between this behavior and another option that would cause the selection of the closest identical object (in this case a note). And to be perfectly honest, I have never benefited from Dorico selecting the nearest object, so I have abandoned this means of navigation/selection. I further believe that Dorioco’s current implementation of this is geared toward selecting things to “tweak” them in Engrave Mode, but it is not very helpful in Write Mode (at least to me).
I remember Daniel mentioning in another post that one of the strengths of Dorico’s different modes is that the same shortcut/control could be mapped to do different things in different modes. Wouldn’t it be cool if the cursor arrow selections just automatically selected the nearest identical object in Write Mode and keep the current behavior as it stands in Engrave Mode? (I’m not sure if this is possible, or even desirable for the team to implement, but I would find it helpful). 
My current practice is to scale the music down (I use galley view) and lasso the items I’d like to select (if it’s all contiguous items). The trick is the larger the score, the smaller the zoom will be, necessitating careful selection technique. (especially if you are on a laptop with no mouse) 
I also agree that the arrow selection is extremely not reliable and useful and I almost never need to select an individual slur/articulation with the keyboard when I’m coming from a note. A simple “notes only” navigation option to check in a menu somewhere would be invaluable.
+1 !
I really like musicmaven’s idea that the arrow keys could function differently in Write mode and Engrave mode. That would be really helpful, and probably no less intuitive than the current system. Also, it helps to capture the difference between the two modes, and the advantages of separating the modes.
+1 with Stephen and Musicmaven
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I just had a situation where I was unable to leave a bar and select something in the next bar with the right arrow key. The selection kept jumping back to the start of the bar no matter which arrow keys I pressed. (I can’t reproduce it though.)