Has it been reported that natural harmonics are pushed up above ottava lines when both features are used in conjunction? This is definitely contrary to any convention I’ve encountered.
Unfortunately this is (at least for now) an inevitable consequence of the way that playing techniques are handled versus slurs-octave lines-tuplets-articulations (which are all handled together). You’ll need to move the harmonic inside the octave line in Engrave mode (at least for now).