For what it's worth, I made the code more Perlish and incorporated the fix proposed by the others:

use strict;
use warnings;

system 'cls';
Menu_Main( 10 );


sub Menu_Main {
    my ( $SWOS ) = @_;

    #$arr = Text to display, Menu position/selection#,  Menu Section, 
+Numerical Reference
    my @arr = sort { $a->[ 1 ] <=> $b->[ 1 ] || $a->[ 2 ] <=> $b->[ 2 
+] }
        $SWOS == 10 ? [ 'First',       8, 1, 27 ] : (),
        $SWOS == 10 ? [ '5x First',   13, 2, 28 ] : (),
        $SWOS == 10 ? [ 'Second',      9, 1, 29 ] : (),
        $SWOS == 10 ? [ 'Third',      10, 1, 30 ] : (),
        $SWOS == 10 ? [ '8x- Fourth', 21, 3, 31 ] : (),
        $SWOS == 10 ? [ '5x- Fifth',  17, 2, 32 ] : (),
        $SWOS == 10 ? [ '8x- First',  18, 3, 33 ] : (),
        $SWOS == 10 ? [ '8x- Second', 19, 3, 34 ] : (),
        $SWOS == 10 ? [ '5x- Fourth', 16, 2, 35 ] : (),
        $SWOS == 10 ? [ '8x- Third',  20, 3, 36 ] : (),
        $SWOS == 10 ? [ '5x- Second', 14, 2, 37 ] : (),
        $SWOS == 10 ? [ 'XXX- First', 23, 4, 38 ] : (),
        $SWOS == 10 ? [ 'Fouth',      11, 1, 39 ] : (),
        $SWOS == 10 ? [ 'Fifth',      12, 1, 40 ] : (),
        $SWOS == 10 ? [ '8x- Fifth',  22, 3, 41 ] : (),
        $SWOS == 10 ? [ '5x- Third',  15, 2, 42 ] : ();

    my @menu = ( '', '5x & 8x Series', '5x Series', '8x Series', 'Othe
+r' );
    my $menuidx = 1;
    print 'Select [1-' . @arr . "].\n\n$menu[$menuidx]\n";

    for my $i ( 0 .. $#arr ) {
        if ( $arr[ $i ][ 2 ] != $menuidx ) {
            print "\t\t", '-' x 58, "\n$menu[$arr[$i][2]]\n";
            $menu = $arr[ $i ][ 2 ];
        }
        #print "\t\t$arr[$i][1]. $arr[$i][0]\n";
        print "\t\t", $i + 1, ". $arr[$i][0]\n";
    }
    print 'Selection ==> ';
    chomp( my $ANS = <STDIN> );
    if ( $ANS < 1 || $ANS > @arr ) {
        warn "$ANS is not a valid menu selection.\n";
        return;
    }
    # Print elements in array
    print 'Array count #1: ' . @arr . " \nProcessing ANS: $ANS\n";
    my $MMANS = $arr[ $ANS - 1 ][ 3 ];
    # Print Elements in array again
    print 'Array count #2: ' . @arr . " \nMMANS is: $MMANS\n";
}
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