Trills on harpsichord

I just bought the app (which is great!), but after buying the harpsichord all notes with trill or + markings are muted. They work fine on other instruments. Anyone else noticed this?
There is quite a lot of trills in harpsichord music, so this is a nuisance...
There is quite a lot of trills in harpsichord music, so this is a nuisance...