Well, the Russians have just 200,000 troops spread over 3000km of line of contact with Ukraine, plus some airborne troops that can strike from deeper inland. I think your expectations of "massive" will have to be adjusted somewhat, at least until the Russians bring in more forces.Something definetely smells fishy. No mass artillery attacks, no mass tank attacks, no massive infantry attacks, no.massive air attacks etc. No massive anything.
It doesn't seem to be what a proper general offensive to invade a country is supposed to be. Its more of probing attacks than anything else