Can't Get msirgb To Do Heartbeat

I am running Manjaro Cinnamon on a B450 Tomahawk Max based PC. I cloned msi-rgb and compiled it. It runs fine, but the example code in the README.md do not work as shown. In particula, the “heartbeat” example doesn’t look like the embedded GIF; it instead is dark, flickers goes white, flickers a bit, goes dark and repeats. Help!

(I’ve tried OpenRGB and it’s far less feature-rich.)