So what phase are you executing that code in?

http://cpansearch.perl.org/src/DROLSKY/HTML-Mason-1.47/Changes

   - $m->flush_buffer is now ignored when inside $m->scomp or $m->cont
+ent. Patch
  by Frédéric Brière, with extra tests from Ruslan Zakirov. RT #389
+24.
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