It maybe that your spreadsheets have cells with spaces in which are overwriting earlier spreadsheets. Run this to check

#!/usr/bin/perl
use strict;
use Spreadsheet::ParseXLSX;

my $target = 'Target.xlsx';
my @file_list = glob "*xlsx";
my @target=(); 

for my $file (@file_list){
  next if ($file eq $target);
  print "Scaning $file\n";
  my $parser = Spreadsheet::ParseXLSX->new();
  my $excel = $parser->parse($file);
  
  for my $sheet ( $excel->worksheets ) { 
    my $name = $file ."_".$sheet->get_name;
    my ( $row_min, $row_max ) = $sheet->row_range();
    my ( $col_min, $col_max ) = $sheet->col_range();

    for my $row ( $row_min .. $row_max ) {
      for my $col ( $col_min .. $col_max ) {
        my $cell = $sheet->get_cell($row,$col) ;
        if ( $cell ){
          my $val = $cell->value;
          if ($val =~ /\S/){ 
            if ($target[$row][$col]){
              print "WARN: Overwriting row: $row col: $col val: '$val'
+\n";
            } else {
              $target[$row][$col] = $val;
            }
          } else {
            print "INFO: Skipped blank $name row: $row col: $col value
+: '$val'\n";
          }
        }
      }
    }              
  }
}
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