Just logged back in, and a fresh set of litter is strewn about my island 15 hours after clearing away the last lot.
However, the 'quest' that should come up telling you to clear them has not appeared (remains stubbornly absent after refresh/cache clearing) so I have no target figure to aim for, no clue as to current progress. Difficult enough when it 'works properly', probably if I bothered to look, would probably already find this filed as "No Bug" on the accursed test server.