Day 5 absolutely DOES NOT guarantee a combo from daily blessing. Strangely, day 5 WAS always a combo following the 3/17 blessings update. But no announcement was made. The 3/20 blessings update both announced the change to guaranteed combo on day 5 AND changed it so that this was no longer the case. Clearly it's not working as intended, and I think I speak for the vast majority of players when I say that we'd all like it fixed as soon as possible.