I used to run 3 even splits on my 49" ultra wide (1706 pixels wide). I started playing a game recently that wanted a 1920 px window, so I made adjustments (1600, 1920, 1600). The taskbar lines up (only on center split). When I open the start menu, it slides open as normal, then jumps 106px to the right (where it used to open with even splits).

I've rebooted (the newer profile is default) and same thing. I've loaded the older (even split) profile and the start menu opens as normal again. It's not that disruptive, just strange.