Maximum Date/Timestamp

I am not seeing the behaviour you show in the second image, although I have tidied up the formula a bit at this end.

  1. Move the formula to another sheet, google forms responses do all sorts of strange things.
  2. When removing data from responses, remove only the data, not the rows. You are correct in clearing the data regularly, this will keep the formula response time down.

Use this: (paste it to your responses sheet cell, then you can cut and paste to another sheet and the range links will follow.)

=sort(filter($A:$D,match($A:$A,query($A:$D,"Select max(A) GROUP BY B ORDER BY max(A) desc LABEL max(A) ''" ),0),match($B:$B,query(query($A:$D,"Select B, max(A) GROUP BY B ORDER BY max(A) desc LABEL max(A) ''" ),"Select Col1"),0)),1,FALSE)