i have a lot of similar issues, and was actually going to make a post about this myself to see where it was on the Dev's priority list. The UI in general is unresponsive; i find it takes several clicks to get units moving sometimes. looking closely at my melee units, even on the front lines they tend to just start standing around doing nothing. my hero managed to get stuck in the mountain terrain once when i was spam clicking him trying to get him to attack to get exp.
I noticed that the game can only process one unit move at a time. if i select them all then click somewhere you can really see only one battalion move forward, a pause, a second battalion starts moving, another pause, the third battalion moves, and so on.
as a result, i plan on avoiding pvp up until it gets fixed. I could deal with not getting any new content, no other bug fixes for a full month if only this issue was fixed. After all, what is an rts with lackluster combat?