VST instruments play 1 octave higher than written

I’m trying out Dorico and very interested in switching to it for multiple reasons. But
I’m having a simple problem, which is that all the written notes play one octave higher
than written. Doesn’t matter if I input them, or if I play from a tutorial-provided score –
one octave too high. What’s up?

Welcome to the forum, cbmuse53. Playing a tone or two too high is a common problem, because it can be that there’s a mismatch between the sample rate shown in Edit > Device Setup and the actual sample rate used by your audio hardware, but I don’t believe it’s ever the case that it can be an octave out. Worth a look, though. You find this to be the case even if you open one of the provided example projects and play it back with the included HALion Sonic SE 3 plug-in and its factory sounds?

Is your score using the tenor clef or other octave-altering feature?