Re the Pulse Wave Scanner thing, it definitely seems to be some kind of lag in loading the core asteroids - that is, whenever you move, the glowing asteroids don't glow until you've been close to them for 30s or so. Hence, if you are moving quickly, they don't show as glowing until you're next to them or you've past them.
As to why, my guess is that they've gone from locally cached database of depleted asteroids (loaded when you drop from supercruise), to an 'just-in-time' update from the servers to remove the 'respawning cores' issue (one can imagine a continuous update whenever a ship moves is very taxing on the servers, so they probably only update a small area for each client). This means that the glowing asteroids can't update until your game instance has received the data from the servers, which causes this lag.
Unfortunately, this 'fix' means core mining is very broken. It was already time consuming finding cores, which wasn't itself unreasonable, and the good thing with the PWS is you could get very good at spotting cores from a distance with experience, making the gameplay element quite fun - there was something to learn and get experienced at, plus it is rewarding to be able to spot a very distant asteroid and know almost instantly it just looked 'right' to be a core. An inability to spot cores at a distance ruins this experience.
It also makes core mining very inefficient, which is regressive I think in terms of gameplay. At least core mining did involve some actual gameplay with spotting the asteroids, as mentioned, and then maneuvering to plant the seismic charges (on sometimes rotating asteroids) and shoot off the revealed subsurface deposits once the asteroid was cracked. But with the PWS broken, core mining is going to be largely dead, pushing everyone back to brainless laser mining of painite.
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