Please read description from bug Bug 37008 which was filed for windows
Bug 37008 was filed for OSX, sorry.
[Reproducible] with "LibreOffice 3.4Beta5 – WIN7 Home Premium (64bit) German UI [DEV300m103 (Build:5)]". Tried to open sample from "Bug 37008 - Staroffice-Import-filters <= 5.0 unavailable" (with activated experimental functions, of course), but there is no .sdw listed in file types and when I try to open the ASCII filter options filter will appear. I can open the document, but the result is unusable. OOo3.1.1 opens the document without problems. This should be fixed soon, but I do not see this one as a 3.4.0 blocker.
It was fixed by this commit: http://cgit.freedesktop.org/libreoffice/bootstrap/commit/?h=libreoffice-3-4&id=6db1c0424120dec7c2bcac5c01c2918f978ce4f3