Here is a Short, Self-Contained, Correct Example for you to try and then adapt to your situation and hopefully demonstrate the problem.

#!perl
# c:/path/to/dirapp/test.pl
use strict;
use warnings;
use FindBin;
use lib $FindBin::Bin.'/myperl-lib';
use library_sub;

print test();
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package library_sub;
# c:/path/to/dirapp/myperl-lib/library_sub.pm
use strict;
use warnings;
use Exporter qw(import);
our @EXPORT = ( 'test' );

sub test {
  return "library_sub::test - OK";
}

1;
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