I should add that both monitors are connected via DisplayPort. Also, I found that cheap DP cables can really mess things up. Eventually I found via the VESA website which manufacturers have their cables certified. My go to is called Accell, very solid ever since using their cables.
Hey, glad it took off and got you and Lunar some exposure. I’m grateful for it being available free and solving a rather large annoyance. You are obviously very talented, keep up the good work!
The only issue was with the "Read external monitor brightness periodically" preference, which froze the system. But there is a fair warning.
If you feel like supporting the author, here is his Patreon:
https://www.patreon.com/alinpanaitiu