From Olivier Ronez: “I had a hard time to discover why there were strange false positives in Grammalecte, and the reason is that it seems that the grammar checker begins to work before Hunspell is ready to answer. At the beginning of checking, when Lightproof/Grammalecte asks to analyze words morphology, Hunspell may answer nothing, and the grammar checker stores in "analyzes" an empty list for several words which exist in the dictionary. This may have no consequences at the moment (it depends what the rules are), but later when the grammar checker ask to analyze these words it still uses the empty result stored in "analyzes" and false positives may occur again.”
http://cgit.freedesktop.org/libreoffice/lightproof/commit/?id=e53961f0481c7e1d11d9f92ef9eb7a6fe17405b7
Laszlo Nemeth committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/dictionaries/commit/?id=3938d334ff4ce612a01b8cc178b0e79782577a62 fdo#57461 fix Lightproof/Hunspell synchronization The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.