This is a bigger bug than people realize. After like 2 stacked waves, they will stop spawning in that lane in general, causing the other team to lose a ton of souls.
E: from minute 3 to minute 7 we didn't have lane souls to get in this game 18669240
It plays the sound, but gives no souls. Also, I've noticed denies are now split evenly between laners. Last patch it was giving both players full souls.
Something funky is happening with soul splitting in base late game after the last patch. If the whole team, or most, are within split range, you'll only get like 7-10 souls per minion. If it was an even split it would be double that, if not more.