I used a slimmed-down version of your script, trying to make it as simple as possible. This works for me.

#!perl

use strict;
use warnings;
use Devel::SimpleTrace;
use Test::More tests => 2;
use Test::Resub qw(resub);

{

    package BossClass;

    sub show {
        my ( $class, $message ) = @_;
        return "$class, $message";
    }
}

package main;

{

    sub create {
        my $obj = $_;
        my $res = $obj->do_it;
    }

    my $mocker = resub( 'BossClass::show', sub { 'show' }, capture => 
+1 );
    is( BossClass->show('no_go'), 'show' );
}
is( BossClass->show('show'), 'BossClass, show' );
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