Dynamic markings / Velocity settings do not work

Windows 10, musescore 4.2.1, soundfonts installed, all that.

I struggled to find anyone else noting this or having this issue - the search function on this site is nearly unusable - so apologies if I'm not the first or if there's a solution out there.

Reinstalling musescore, musehub, and rebooting my computer hasn't done anything. No matter what dynamic markings I use or manually set the velocity to, the playback outputs the default. This applies to all of my scores. Every soundfont. It's all the same. I cannot say if it was present before 4.2.1 either.

I've included the score I worked on when I noticed this, where I have tweaked the velocities to extremes in the first few bars. It would be great to know if the problem is local to me, or if it's with the score.

Thanks in advance.

// Upon further tinkering, I found dynamics to work in some scores, sometimes. Velocities are still unyielding. I have no idea what's causing unreliable dynamic markings, still.