I have LO 6.3.3.2 on Xubuntu 18.04, up to date, except that I downloaded it from LO rather than install the version in the Ubuntu repositories. The display is UHD (3840x2160).
I usually use only Writer, which I have in a window by itself, along with Formatting and Styles toolbars floating off the window (see screenshot below). As you can see the Styles palette is illegible because the line spacing is inadequate. Interestingly, if I go into Tools > Options > Personalization and select any theme the text in the palette immediately rights itself and appears with correct line spacing. But the second I close the Options window the line spacing changes back to being illegible.LibreOffice_Screenshot_2019-12-27.png
In an effort to work around this problem I decided to try Tools > Customize, but when I click on it the entire program hangs. All my other applications work just fine. I need some ideas. All suggestions gratefully received!