MuseScore 3.1 mixer patches are not being correctly saved/loaded on/from score

Patches chosen on the mixer are being messed up when loading a score. Especially the ones with multiple soundfonts and/or sfz files attached to it.

Furthermore, all strings patches selected as, e.g. violins expr., violins II expr., violas expr., violins pizzicato come back to their default values after loading a saved score, i.e. strings expr., strings expr., strings expr. and strings pizzicato, respectively, for this example.