What does @a_ff1 have in it?

use Data::Dumper;
if ($ff1) {my @a_ff1 =  &GetRow("$ff1"); print Dumper(\@a_ff1)};
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This works as expected for me. Start with this, then keep adding code until the problem arises:

use strict;
use warnings;
use Data::Dumper;

my @a_ff1 =  &GetRow("foo");
print Dumper(\@a_ff1);

sub GetRow {
    my @ary = 0 .. 3;
    return @ary;
}

__END__

$VAR1 = [
          0,
          1,
          2,
          3
        ];
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See also Basic debugging checklist