Could the issue be our underlying mantra of "Clear and Obvious"?
For green 5, when his run starts he's onside from the ruck and when the kick is taken, it's not c&o to the ref that the offside player is material so we play on and we're now focused on the active players, looking for clean tackles, obstructions, desperately trying to remember that infernal newfangled framework, etc.
Phases occur or metres are covered in this case by which time green 5 is now in a useful position - but to us it's just another green player who looks onside to us - so we play on.
Green 5 now becomes material but we either don't remember they were offside at the kick and haven't put themselves back onside while our back was turned or we feel it's so long after the original event we just don't think of 10.b?
Contrast that to the cases where we have a kick and a player is further down the pitch and our "c&o" bell starts to go off and we start getting all twitchy about the 10m law. Now, when that player drifts into play we're already primed and decide to whistle, signal a PK, point to offside and then state "<color><#>, you were never onside."
(As for the shove - I guess it would depend on where I was positioned. If I was chasing from behind and saw the shove I'd be happy to call that foul play. But if I was chasing this from the side, maybe at a 45 angle to the runners left, then it may be I just can't see the shove or I think it was a legitimate shoulder to shoulder - not c&o so off we go...)