Old auto-complete levels no longer work?

So I've noticed old custom levels that auto-complete (e.g. Cruise Control, There and Back Again Machine) don't seem to work anymore, even though I definitely remember them working years ago. Anyone have any idea why this might be? Was there some subtle change in the game's physics, maybe between PlatinumQuest and the OG Marble Blast Platinum, that broke them?

I Believe These Levels Still Work In The Normal Marble Blast Gold But Not The Web Port Version Of MBG