I'm a long-time C::MM user and contributor, and at first glance, your code looks fine.

You might want to double-check that the expected methods are being installed as you expect. You could add a logging install_methods in your subclass:

  sub install_methods {
    my ($class, %methods) = @_;
    my $target = $class->find_target_class;
    my $methods = join ', ', keys %methods;
    warn "Installing $methods in $target\n";
    $class->SUPER::install_methods( %methods );
  }
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