I have a 4k split into 4x 1080p displays. I use "Mirror monitor with splits" to create a "virtual" screen, which I can then share in meetings so people with lower resolution monitors see a reasonably-sized image. This works great in Microsoft Teams, but GoTo freaks out. "Move this window away from the shared application" flickers on different applications that are nowhere near my "virtual" screen.

Is anyone successfully using "mirror monitor with splits" in GoTo Meeting?

Yes - I can share any other app I've tried, but when I try to share a mirrored portion of the screen, that's when other apps start to "flicker" with the message that they are blocking something else from being shared.