At home I have a three-monitor setup. Just updated to 3675 from 3674.
Initially, when my third screen is connected, starting Cantabile just had a white window, which I have to forcibly close. If I disconnected the third monitor, it starts fine.
With two screens connected, I then moved the running instance over to first screen, close and restart. I saw the same problem.
I then positioned Cantabile to the second screen. When I restart Cantabile it works no matter what monitors are connected.
At risk of generating a “smug report”, would this help?:
I may have seen something similar in recent builds, but just copied over working settings fil without looking at monitor setup.