Musescore 4 Playback downgrade

I am working on my arranging skills in the barbershop style and have been using musescore for about 2 years, maybe a couple hours a week.

I am incredibly frustrated with the Musescore 4 playback system. In Musescore 3, I can use my midi-keyboard and hold a note, and as long as the selected instrument can realistically hold, the note will continue playing. This is useful, as I oscillate between the possible chords and the possible voicings.

In musescore 4, at least by default, all notes simply just stop playing. Additionally, instruments appear to have a blocked out range that cant be exceeded? Is that an attribute of the Musesounds VSTs or is there some setting? I cant get my brass instruments (I use the trumpets to arrange barbershop often, because the singers are simply not fast enough to hear the chords lock) to play, for example, G4. My guess is that is a setting that I have wrong, but if it is, I cant find it.

When I play notes in musescore 3, they are highlighted in the piano panel - uniquely helpful so I can just look at the screen to see which notes are playing, so I don't have to look back and forth between my desk and the score - I am not a piano player - so I can make the simple note adjustments with my hands.

In musescore 4, this is SO SLOW and not nearly as clean, not to mention the times when it will leave notes highlighted that are NOT being played and sometimes will fail to trigger on the screen despite the sound being played.

Is there something I need to install to make this work the way it should? There is a substantial aesthetic upgrade in musescore 4 and I would like to use it, but these functionality flaws (primarily the former, not being able to actually hold a note down and have it keep playing is so painful) means that I cant arrange in Musescore4 at all.

What am I missing?