Square synthesizer sounding weird

The square synth is one of my favourite electronic instruments on MuseScore 3, but recently I've noticed that it sounds different sometimes when I add other instruments to an existing score. I'm not quite sure how to explain it, but instead of having a crisper, fuller sound, the synth will sound more like an electric piano.

Usually I could just close and re-open MuseScore 3 to fix the issue, but this time it didn't seem to work. Does this only happen to me, and how can I resolve this?

>> I left an audio file below of the way the square synth normally sounds (0:00-0:07) versus its altered sound (0:08-end)