Mac 10.14? Cause I'm using Mac 13.3 is if you're using Mac 2017 Ventura and trying to figure this out this will work for you as Window Capture does not unfortunately.
Heh, I wonder if the Syphon update I was reading meant macOS 14 (or I just messed up), but yeah, things have changed for newer macOS versions. Both the information you shared and the information I shared will be useful to anyone using macOS, use whichever one fits your situation. I'm on 15.1.1 and Syphon absolutely no longer works, but the built-in "macOS Screen Capture" does.