I'm having this kind of problem too. I have a worksheet with 66K+ rows of
data. I'm trying to apply auto-filter to one of my columns (which I
triple-checked to have not skipped any blank row) and the drop-down only
shows less than half of the choices available for my data. I know it's less
than half because what I'm supposed to be choosing are dates (the column data
is formatted in the same way). I can do a few run-arounds but this puzzles
me. Any idea what this is? Is this a bug or a normal auto-filter range
limitation?