Dynamics not working on certain instruments (maybe a grand staff issue?)

I'm working on a score and certain instruments (marimba, piano) don't seem to be working properly on playback and the velocity is stuck on 90. The part starts in ppp with a hairpin to mf. Crescendos and decrescendos also don't work. I've tried resetting velocity settings of the entire score (which only resets the velocity back to 64) and revert to factory settings to no success. I've also tried copying the part to a new score and re-adding the dynamics, to no effect, I've uploaded this new score below.
I've also tried adding new instruments and copying the part. It worked properly when I copied it to a flute part, but reverted back to 90 once I switched the instrument back to piano, and it only worked properly once I manually rewrote every note and dynamic marking, which is arguably not the best solution.
I've read that MS4 treats grand staves dynamics different than MS3 did, so I tried adding a new piano part (the original part in my score only uses the upper staff) and adding the same dynamics to both parts (and eventually I copied the entire part to the bass staff), but it still didn't work.
My guess is it's something related to this grand staff treatment change? Or maybe to the instruments themselves?