Hi,
It would be great if when you are in sketch mode, that selection will prioritize the geometry of that specific sketch.
As it works now, if you have 3D-geometry "above" your sketch plane, F360 will select features of the 3D geometry rather than what you are sketching. You will need to long-click in order to manipulate your sketch lines, use the slice option or turn the light off on the body. Often times when I design something, I want to adjust my sketch depending on the 3D, which means a lot of switching on/off the slice or bodies light bulb.
Additionally, I don't know if I'm doing it wrong, but I cannot double-click dimensions to edit them if they are underneath the 3D-model. It seems you need to activate the dimension tool to do it (or hide the 3D-model).