Notes missing from sextuplet, musescore 4.0

Hello! Musescore 4.0 is freakin awesome!

I am using Mr. Michael Andrew Seaton's transcription of Fanfare pour "La Peri" which is here: https://musescore.com/user/14072251/scores/6586013

I'm attaching the one I saved in musescore 4.0 that I at least got the muse sound instruments picked out. I'm having a few issues:

At the end, the trumpets have a sextuplet. In playback, I can only hear the second half of it being played; the attached picture circles the notes I think aren't reading. While I don't have the same issue in Musescore 3, it still sounds weird, so I'm wondering if this is a score error and not an issue with the program. Wondering if Mr. Seaton used the PDF converter to start with and that caused issues unseen. Anyone else hear the issue?

In playback with musescore 4, when I select the note I want to start the playback from and hit play, sometimes it starts at the beginning of the song, sometimes it starts where I selected and only plays that instrument, and sometimes it plays all instruments starting from that spot. From Musescore 3, I have a habit of clicking off the page, then clicking the note I want to start on, then clicking play. Does that mess something up with 4.0? Is there a different way to start playback in 4 other than selecting a note to start from?

I have a feeling sounds will get more refined with time. It sounds like the horn in F sounds are... blatting? Maybe above a certain dynamic? Don't get me wrong; this piece is perfect for showcasing how much more emotional musescore 4 is vs 3; its several worlds different, glad they took their time in development.