File > New > Database brings up a blank window. The dialog box for creating the new database opens behind this, and in order to find it I have to do a three-finger down swipe (App Expose) to make visible all LibreOffice windows and dialog boxes currently open. Can’t even use the Window menu, because all menus except LibreOffice and File disappear when selecting File > New > Database.
I did a screencast showing what happens.
I turned off OpenGL and restarted LO to see if this made a difference. It didn’t.
LibreOffice 6.0.2.1
Mac OS High Sierra 10.13.3