Half of the houses on my block have gone missing from Zillow!

When you redid the algorithm a few months ago, you "lost" half the houses on my block.  At the same time, the Zestimates all dropped.  My concern is that the loss of half of the data points is responsible for some of the shift.  I am sure you've had lots of people complaining that the new Zestimates are below market . . . but my concern is a little different.  What happened to those houses?  I live at 115 Rockland Avenue in 19072.  You are missing data for many of my neighbors, but prior to the new algorithm you had data for each house on this block.  What gives?  Do you ever go back and review cases where this has happened?  It seems clear that less data cannot be more accurate than more data  . .