[Dovecot] Strange behaviour for sieve_before

Hi all, i moved from dovecot 2.0.15 (lda) to 2.1.5 with lmtp transport, all works well with the same configuration directives.

But sieve_before stopped working with mail_debug=no. The weird thing is that, with mail_debug=yes the sieve_before script starts working.

Any idea? Thanks

(my conf attacched, for the new install i used prebuild packages)

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