I recently upgraded to Finale 25 after years using Finale 10, plus bought a lot of Garritan instruments. When I use Aria as a standalone with my keyboard plus Mac OS 10.13.5 and Garritan instruments, I can load the Garritan instruments (JABB, PO5, etc.) into a given instrument--or load a given ensemble into a bunch of instruments--without problem. However, no matter which instrument slot I then choose to be triggered by my keyboard (i.e., the little light showing at lower-left of the slot), only the first instrument of the bunch will be heard: I can never generate the second instrument's sound even if its light is selected.