I originally tried this in X9, hence no problem. However, I get the same OK results in 8 (not X8, just 8) X6, X7, and X8. X4 gave some writing tools error. ... singular verb is. where "is" is highlighted in blue as in what Christian_h posted. Or reversed image or whatever it's called. In any case, I did not see this problem in any of my WP versions In which Grammatik would run.
Could it be a font size or video setting or other that prevents some from seeing the reversed images? Dunno, just asking.