Screens don't restore properly after sleep
I'm seeing a strange problem recently, which may relate to a hardware change but also might be a Big Sur issue, though I haven't found any reference to it. Here's the story.
I recently upgraded my late-2014 Mac mini to use two 2560x1440 gaming monitors, replacing the two older 1080p monitors. In the process, I found that the mini-DP-to-HDMI interface I'd been using only supports up to 1080p, while the native HDMI port supports 4K. So, to allow both monitors to work at their designed resolution, I switched to DP for both monitors, per Mac mini specs, and it works great -- full 2560x1440 on both screens, nice and crisp.
But here's the problem: about half the time, when I wake it up after sleep, one or both desktops are empty. Mission Control shows all the open windows, but even if I click on one, it goes away once Mission Control does. The only solution is to move it, within MC, to the other screen, then restore, and it will appear, at which time I can slide it back where it belongs. Since I usually have five or six open windows at a time, it gets to be a real pain.
I thought I'd found the problem when I discovered the Spaces settings, and un-checked the "Rearrange" option, but that didn't work.
Has anyone else seen this problem?
Mac mini, macOS 11.0
