Cresc./dim. are ignored for tremolos.
This is coming from my forum topic on this issue; Jojo-Schmitz recommended I put it here instead.
Instruments such as piano, drums, pitched percussion, etc., are not affected by the new single notes dynamics, and rightly so, as they cannot produce volume changes across a single note. However, as Jojo and mike320 pointed out, a tremolo is merely a series of smaller notes played rapidly over the notated duration (e.g., a whole note with a 32nd note tremolo). My question: Why not find a way to get MuseScore to treat tremolo'd notes as a series of notes instead of a single note? That way, hairpins would work normally with them. This may be a minor issue, sure, but I've heard plenty of orchestral tracks that use crescendos in their drum rolls. Might be worth getting this into MuseScore.
Steps to reproduce (as a formality):
1) Create a new score using piano or pitched/unpitched percussion
2) Make a note with a tremolo
3) Add dynamics before and after, with a hairpin between them, like you'd do for a series of notes
4) Hit play. The hairpin is ignored.