Windows 11 26H2 X64
When I upgraded beta 3, I noticed that the titlebar disappeared, despite being enabled in the settings. I still could "find" the button using a mouse over the general region to locate each button.

There are 4 buttons on the Titlebar. Each button moves a window to a specifc screen. I have 4 monitors connected to my computer. Each button points to physical monitor location. So...left for the left-most monitor, center for middle, right for right-most, and top for the monitor over the middle monitor.

I live in Windows dark mode...I use as much as I can in dark mode. Not sure if this is important.

Now, I was able to restore the visability of titlebar when I defaulted the "Button Offset: Horizontal" from -30 to -20. The Titlebar was visiable now, though the icons are stuck on the Display Fusion logo and not 1,2,3,4. The reason for the offset was to slide the titlebar left to prevent overlaying other application buttons in the same area.

Lastly, I was able to recreate the issue when changed the offset back to -30. However, in my attempts to fix the icon issue, I switched everything back to default settings and the visibility issue does not reoccur. (Didn't solve my icon problem... )