Lyrics layout problem MuseScore 3.0.5.5992

I'm trying to create a score in which students are asked to write four-voice harmony based on given chord functions. Instead of using numerals like I, II, IV etc., I use letters (which is the German and Scandinavian way of writing chord symbols) - T for tonic, S for subdominant, D for dominant and adding a 'p' for the parallel chords. I use the Lyrics tool for this, and as long as the chord is in its root position it's no problem, but if I want a chord without its root or in any of its inversions, I run into trouble. The way of writing for example a first inversion dominant would be to first type a 'D' and then enter the 3 below the letter. It looks fine when I create the document, but if I close it and open it again, the document is all messed up (the attached MuseScore file shows my problem, and the pdf shows what the document should look like. The underlined 'Tp' shows that the chord should have two thirds, in order to avoid errors in harmony). I tried fiddling with the automatic placement option, but that doesn't seem to help. The Sibelius software has a built-in font that is specifically designed for writing chord functions, but I doubt it would work with MuseScore. Is there any way I can achieve exactly this? I have seen people writing the first inversion dominant D/3 instead, which I suppose could work, but it's not the correct way of doing it. And if typing it that way, how would I then type the subdominant chord with a 9 to 8 and 1 to 3 suspension?