Thanks @JoPhi — if it’s Safari-based then that makes sense. Aaron’s plugin is Chrome based. The source window point is interesting too and revealed another issue. The “browser” window size isn’t honoring Retina display on the Mac, so even though I have a 6K XDR display, Mimo thinks that the display is only 3000 pixels wide, and won’t let me set the window to 4K resolution! (Yes I’m doing a 4K live show).