The problem was originally brought to attention here (French thread): https://community.logos.com/forums/p/127665/831054.aspx#831054
After investigation, I found that match all word forms (abbr. MAWF) will, in the NASB95 produce horse, horses, etc when I search for "horse". However, in the LSG, with MAWF on, the search for "enfant" (child) does not produce the many instances of "enfants" (children) and vice-versa. I only have one other French resource (Massorah Gedolah: Manuscrit B. 19a de Léningrad) and it does the same thing (try "liste" vs. "listes").
I am not sure whether this applies to French as a language or to some French resources only, or whether the problem is also found in other languages including some English resources.