Ever since Big Sur came along, Lightroom Classic has become intolerably annoying because it just won't stay put on the second monitor. It used to work perfectly with Catalina. Here's what happens to me:
I'm running Lightroom Classic under Big Sur on a 16-inch MacBook Pro with 32 GB of memory and a 1TB SSD drive. I also have external drives including 2 2TB SSDs where my library lives. I have a 2.3 GHz 8-core Intel Core i9. I keep the software up-to-date.
In addition to the built-in monitor, I have an external LG UltraFine monitor that has 3840x2160 pixels.
To get the main Lightroom window on to the second monitor, I must fire up Lightroom using the Dock on that monitor. The Window menu threatens to allow me to move the window there, but if it's on the built-in monitor and I try to use the menu to move it where I want it, nothing happens. The only recourse is to quit Lightroom and relaunch using that other Dock.
So, having gotten underway on the second monitor, I can now open a second window for Loupe view on the built-in monitor. All this works well as long as I stay in Lightroom and don't try to use anything else.
But if Lightroom drops into the background, at unpredictable intervals it will suddenly move itself to the built-in monitor, leaving me with both windows, one in front of the other, on the same monitor. So it's quit and relaunch time again. I'm in that state right now for the third time today so I decided to test the waters here.
Is anyone else having this problem? Is there some magic switch that would make the Window menu work? That would make me so happy even though I'd still be annoyed, but it would be less annoying than having to quit (and possibly go through the save a backup library) and relaunch.
BTW, things get both worse and weirder if I add an iPad as a Sidebar third monitor. Now, Lightroom prefers to move itself to the iPad. But weirdly, now the Window monitor will allow me to move the window but only to the built-in monitor, not where I want it, and it has become tiny because it retains the size it needed to have on the iPad.
Adobe Support blamed Apple. Apple had me reinstall Big Sur but here I am still struggling to do something that used to work with Catalina and which I was really hoping the recent Lightroom Classic update would fix.