Dynamic not working

It doesn't have a velocity change setting (0), that's why. You need 2 dynamics for thor this, an f (or an fp set to f's velocity change, 96) and and a p (set invisible)

You can't get a single note to sound like a real fp. You are forced to make a decision what dynamic you want applied to the note. If you choose f, then change the velocity to 96. You will then want to put an invisible p on the next note so the following notes will be played p. If you choose p then change the velocity to 49 and all of the following notes will be played p also.

Making the velocity 96 and placing an invisible p on the next note works well in fast passages, but on a long note I would suggest that you just use the 49 velocity and live with the lack of the explosive attack you get on the long note.