Muse Sounds playback issues & Timpani question

I just installed Musescore 4. I’ve been having trouble with playback. The first measure wouldn’t play properly. I added an additional blank measure at the beginning and it helped. I also increased the buffer size to the max amount and that seemed to help. It’s still very “laggy” and sometimes playback won’t stop when I hit the space bar. I really would like to also eliminate the extra bar but playback would be an issue. Any advice would be appreciated.

Separate but sort of playback related. The Muse Sounds timpani must be only a set of 4 drums. I put in a B above the bass staff (B3) and it won’t playback that pitch at all. I’m a percussionist and technically the 5th drum should be able to hit that pitch. Is there any way to fix that playback issue?

Thank you.

First post so if I put this in the wrong place my apologies.