Autofilter is switched on, showing rows where the result in column D equals
#N/A. The sheet with the autofilter copies details across from a pivot table.

When the pivot table is updated, the number of rows shown/included may be
different.

Since the autofilter is already on, the only changes that can be seen will
be for those results already shown, i.e. the rows that have already been
filtered. As there may be more results where #N/A is present in column D, is
it possible, to refilter the results automatically? - i.e. reset and then
refilter to ensure that all information is captured and displayed?