Pretty much what Tanktalus said earlier. This code is a vastly simplified example piece that reproduces the issue in question. I tried to trim out as much unnecessary cruft to make the example as small and concise as possible while still remaining relevant

In answer to some of your questions:

1. the way you set up the handler made me immediatly suspicious.

   the live code has some additional processing that happens after the twig is processed. It would look something like the following simplified example:

   sub { my $local_state = _move(@_); $global_state = _do_stuff_with_local_state($local_state->{SUMMARY}, \%VARS);  1; },
2. The, perfectly correct and valid, style to call a sub with &subname

   Correct. The actual code passes extra variables to the twig processing subroutine in addition to the default TWIG and ELEMENT variables passed to the handler:

   sub { _move(@_, $local_state, \%OPTIONS, $warning_flag); 1; },
3. For the rest I can say that, also you have an unneeded 1; as last thing in your sub.

   Pretty much what Tanktalus said earlier.

   The function called by the handler returns '1' in my simplified example (instead of variables) because it is an explicit 'true' return value

   The anonymous sub returns '1' because there are multiple twig handlers that may apply to a given twig:

   '/shipment/box' => sub { _move(@_); 1; },
   '/shipment/box[@location='Vault_111']' => sub { _moveAgain(@_); 1; },
   [download]

Hope that clarifies things.