I'm running into the same issue. Below, I wrote what was happening at this point in time. Then I took a video, and some of the details changed, so view video for the differences.
I have 3 monitors. 1 x 4k monitor with a 4 way split, 1 x 1080p monitors, and 1 x 1080p screen on the laptop. 4k monitor is labeled monitor 3, top left is 3.1, bottom left is 3.2, top right is 3.3, and bottom right is 3.4. 1080p monitor is monitor 2. Laptop screen is monitor 1. Primary monitor is the 4k monitor, so the windows start menu shows up on 3.2. DF taskbar on 3.1 and 3.3 are on top of screen, auto-hide. All other screens have normal DF taskbar on bottom.
Click on Windows start menu (3.2). Start menu always flashes. Sometimes stays open, sometimes "closes" (really it's still open, but invisible). If start menu is open and I start typing to do a search, start menu disappears, but it's still working invisibly. Same behavior if I press start button on keyboard with 3.2 active.
Top of 4k monitor, 3.1 and 3.3. Pressing start on keyboard, start menu flashes on 3.2 (as expected), moves to 3.1/3.3. If I start typing, the search window actually works and is visible, but moves back to 3.2. If I click on the start menu instead of using keyboard, get the same flash on 3.2, moves to 3.1/3.3. However, when I start doing a search, start menu disappears but is still working.
Bottom right of 4k monitor, 3.4. Click on start menu, start menu flashes on 3.2, and then closes. It's actually closed. I can see that the start button on 3.2 is actively selected, and a hover over pop saying "start", like my mouse is hovering over the button on 3.2, but is obviously not. Pressing start button on keyboard with 3.4 active, start menu flashes on 3.2, moves to 3.4, start typing, start menu disappears but the search is still working.
Screens 1 and 2 operate the same. Click on start menu, flash on 3.2, moves to 1/2, start typing, and start menu actually stays on 1/2. Press start button on keyboard, flash on 3.2, moves to 1/2, start typing, start menu stays open, but moves back to 3.2.
I don’t care about the flash on 3.2. However, I really want the start menu to quit disappearing. Ideally, I want all monitors and splits to operate just like monitors 1 and 2 do when I click on the start menu, but want it to work for keyboard button too.
I have attached my settings export. I also took a video so you can see what is happening. Unfortuntaly, after typing everything above, some of the start menu weirdness was actually different. On each screen I pressed the start button, then typed "blue", and pressed enter to open Bluebeam. So even if the start menu disappears, you know what I was doing. Hopefully, this will help you pin down the problem.
• Attachment [protected]: 6MTZX4drdG.mp4 [12,831,256 bytes]
• Attachment [protected]: DisplayFusion Backup (2019-12-27 @ 09-16, 9.6.1.0, A-97LBMQ2).zip [72,761 bytes]