I have glyphs in my design that render faulty when interpolated from otherwise interpolating components. Interestingly, also the decomposed copy of the glyph is interpolating just fine.
The exported files have the same interpolation issue in the component-glyph (n) but the outlines are fine in the duplicated and decomposed glyph (mapped to m here):
It seems whenever I return to try using components the same weird bugs are around to put a damper on an otherwise cool feature… Screenshots taken in 3.1.1 (3139).