I'm running Version 10 Beta 15 as well as version 2022.1 of IntelliJ. I am having an issue where I can't close an IntelliJ window using the X in the upper right. It seems to be behaving exactly like the restore button. See attached video. The only way I can close the window is to right click on the icon in the Task Bar and then click on Close window. I only have this problem with IntelliJ windows.
This works fine if I close DisplayFusion

I am also having this issue. I downgraded to Display Fusion Pro 9.8 to see if that would help. It did not. I did notice that if I hold down the shift key while clicking on the "X" then the close fuction works correctly. If I move it to the monitor that is not split, it works correctly.

I went ahead and turned on logging. In the hopes that this would help you with troubleshooting.

16:37 - Clicked on close (X) and it performed "maximize"
16:38 - Clicked on close (X) and it performed "Maximize"
16:39 - Held down SHIFT While clicking on close (X) and I got the exit confirmation screen.

I hope this helps!

Here is my debug file. Hit X a few times at 1:52.
And thanks to the previous user about the hint to do a Shift-click to close

I am using IntelliJ IDEA 2022.1 (Ultimate Edition) Build #IU-221.5080.210

Same here: 5080-210

Here you go

What is the best way to display the splits but be able to get them back quickly?

I don't know if it is relevant, but when I have IntelliJ running on the monitor which has no splits, everything works correctly.

This problem is still happening. Running DisplayFusion 10.0 Beta 17 and IntelliJ 2022.2.2

This problem is still occuring

This did not get fixed with IntelliJ 2022.3. In fact, I just got a new computer and after re-installing all my software, the problem still occurs. Running DisplayFusion 10 Beta 21 and IntelliJ 2022.3.2.
I can send a video if you want to see it