If the dotted circle filter doesn't find a GDEF statement while trying to make the dotted circle glyph into a base glyph, it adds the glyph to the OPENTYPE_CATEGORIES part of the font's lib instead. If there isn't a OPENTYPE_CATEGORIES lib, it makes one. This is a mistake, because the dotted circle glyph becomes the only thing in OPENTYPE_CATEGORIES, and everything else not in the dictionary is assumed to be base; this is not what you want.
If the dotted circle filter doesn't find a GDEF statement while trying to make the dotted circle glyph into a base glyph, it adds the glyph to the OPENTYPE_CATEGORIES part of the font's lib instead. If there isn't a OPENTYPE_CATEGORIES lib, it makes one. This is a mistake, because the dotted circle glyph becomes the only thing in OPENTYPE_CATEGORIES, and everything else not in the dictionary is assumed to be base; this is not what you want.