Scaler routing problem in Studio One

So weird. I’m an experienced DAW user who has done this sort of thing countless times but having some kind of weird trouble routing Scaler within Studio One to an external/hardware instrument.

The hardware synth can be triggered via the MIDI piano roll within the MIDI track, no problem. The WEIRD thing is that this same hardware synth DOES work with and is responding to other plugins that send MIDI – for example, the fantastic HY-SeqCollection2. This leads me to believe that the issue is not with Studio One or with the way that I am routing things but rather with Scalar.

It’s even MORE weird that I had previous worked with Scaler and had all of this going. However, I’ve been stuck like this for awhile and I’d really like to sort this out and get back to working with Scaler again. Any help would be greatly appreciated!