Dorico doesn't show player's second instrument in write mode

I have an orchestra score where some players alternate instruments (classic Dorico feature…) However, Dorico doesn’t show the staff for the second instrument so I can’t edit it…
When I start a new project and just add one player with two instruments (flute and picc. for example) it’s the same thing, I can’t see the second instrument.
Hide empty stave is in Never.
Very fraustrating…
Any suggestions?

Welcome to the Dorico forum.

Go into Galley view.
All instruments show up there.