Are you sure the CSV data is good? Check that it doesn't contain any extraneous special characters. For instance, a line with just a carriage return and no line feed may cause that problem:

my $cr = chr 0xD;
my $lf = chr 0xA;

print "Line before\n";
print "Line with crlf$cr$lf";
print "Line after\n";

print "Line before\n";
print "Line with cr$cr";
print "Line after\n";

print "Line before\n";
print "Line with lf$lf";
print "Line after\n";
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This prints:

Line before
Line with crlf
Line after

Line before
Line aftercr

Line before
Line with lf
Line after
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