Thought someone else would have picked this up. Huh.
Minor bug fix patch released today.
Drillex animations added [I'm surprised this managed to slip through the main update]
Resolved a problem that caused split-screen to become disabled if players backed out to the “Press Start” screen whilst in Split-Screen
Fully disabled Dynamic Split-Screen mode (This will correct any affected save files)
Resolved a problem with Save Game serialization that was affecting user settings (This would result in all user preference settings (Terrain, etc.) from being different to what was selected)
Also a user reported that the "transparent brick glitch" was fixed. Not sure what this was, though. It could be related to a bug with transparent bricks being completely invisible underwater.
Surprisingly, no reports of the update breaking the game - expect for this person with a report that's been coming up since update 3 and is likely something else causing it.