To me it seems that progress is lost whenever a commercial starts. Whenever this occurs progress for the day is lost and back to where I started.
I notice that Sudoku now plays these (horrrible ) 35 seconds commercials, whereas normally they would take 5 seconds.
So clearly something has changed since these longer commercials run. This has been happening (at least to in my case) since 8 to 10 days.
Hope this helps. Please fix.