Just realized the same. That is poor. Looks like hiarpin has quite no effect and the pp/ff just for the note it is assigned to.
Looks like the score editor is more decoration than a real score editor which can be used to define accents etc.
I tried also with Notion. There it works. If you send it to Studio One it does not influence velocity. The only what then is to send Midi, which does not keep the hairpins etc.
For me it means this "decoration" is in Studio One just decoration and does not work.
