I've often found myself in the position of wanting to send units near a power generator I already control. However, even within seemingly inches of a power generator the click still selects the power generator. This, I believe, is telling the units to take the generator. But if I already control it, they don't move. The area selectable for a power generator needs to be cut down. This is a very frustrating mechanic for me as I keep clicking further and further away until I actually have a point on the ground selected.
I hope this makes sense! Thanks!