No sounds from some instruments

Using 3.5 on macOS 10.15 with a Komplete Kontrol S88 keyboard.
I can’t get a couple of instruments to playback with the midi keyboard.
I have several instances of BBSO loaded and they play fine with the keyboard. I have a Spitfire Audio Labs instrument and a NI Komplete Kontrol instrument loaded that do not make any sound with the midi keyboard (or through playback in the score). They appear to be set up the same as the instruments that work. They work in stand alone too. I attached a picture.
What else can I check? Thanks

Is the Endpoint Setup all correct with you? In the right column where all the VSTinstruments are listed, left to the instrument name is a cogwheel icon. Click on that and the Endpoint Setup dialog appears, where you can set things like number of MIDI channels and the like.

Well I found a instance of Haleon Sonic in the vst list that wasn’t being used. Once I removed that the other apps started working. Weird

if you make changes to your instruments setup after loading in the playback template/saved project, then a Halion instance will be created (unless you changed the default playback configuration). I’m just wondering whether there are other circumstances in which this can happen as I’ve seen it a few times in situations when I’m pretty sure I did not change the Setup. Additionally, my understanding has been that if you remove the assignment from an instance (because you can’t actually delete it unless it’s the last one), when the project is next opened, these blank instances should have been removed. I find some inconsistency here and wonder whether Ulf could again be kind enough to clarify exactly what behaviour should be expected on this point.

As Ulf says, any problems with tracks not actually being played back are nearly always attributable to errors in the Endpoint.

Im brand new to Dorico. But this is one area I find very confusing. I read the section of the manual but only once so… I’d really rather be able to add a player and my own instrument, not have to pick from the pop up list.

Anthony, you can’t define your own instruments from scratch in Dorico as yet, but this is something we anticipate making possible in a future version of the software. For the time being, use the closest existing instrument, change its name, and change its playback sound.