I have this problem
when I try to search in StartIsBack++
I also encountered a glitch where the Minimize, Maximize & Close buttons are showing the Arc themed buttons, and not the Placebo X design. I fixed this by scaling to 100% then I scaled back to 150% or to the default scale.
Also the "Color" in Reboot/Restart animation, stays on the default Blue Color of Windows 10 and not the color that I chose in the Settings.
I hope there's plans for Dark Modes in 1803, since I can't choose to upgrade due to limited internet data and the unavailability of the 1809 update itself. I could force upgrade using a program by Microsoft, but limited internet data still stops me.