I tried Segoe UI 14, and the button doesn't get misaligned for me.
It might be of help if you can figure out why that is happening for you.
The vertical misalignment of "MusicBee" in the button is only visible with some fonts (*), even with
row padding = compressed,
but not with Segoe UI 14 for example.
Anyway, it doesn't affect the presence of the black line over the track title.
(*) Such as: Ubuntu, Papyrus, Comfortaa, Commissioner, Kristen ITC (not shipped with Windows).
From the tests performed so far, the only factor triggering the black line is the size of the default font.
And the larger the default font, the thicker the black line.