Mixer not appearing (musescore 4)

Mixer stopped appearing, tried so many things don’t know what to do.

So I recently started using Musescore 4 it has worked fine for me for a bit, but the instrument volumes has been a bit wonky, so I usually fix that manually. Today however the mixer has just stopped appearing

I don’t mind writing with the volume being weird but I need to send a sample to a client soon. How do I fix it. It says that the mixer should be visible even though nothing has appeared on screen. Does anybody know anything? I also have had issues with the playback playing this that are not in the score.