There seems to be a bug in the harp pedaling feature, which was added in Dorico 3.
When you add harp pedal to the treble cleff, it doesn’t also automatically apply to the bass cleff. And vice versa.
You have to add harp pedal to both the treble and bass cleff.
That doesn’t make sense —
I have a Dorico file that shows this, but I can’t attach it.
Clearly there’s something wrong with the harp instrument in your project. I suggest you create a new player holding a harp and copy and paste the music from your broken harp into the new harp instrument. You’ll need to copy the music one staff at a time, since Dorico pastes instrument-wise and not staff-wise.