In my LO version (184.108.40.206) I don’t see the lines in the horizontal ruler in top, they are probably white and, therefore, invisible. Is there a setting for that?
I am having this same issue (Windows 10, LO Version: 220.127.116.11). It really annoys me because I am mildly obsessed with formatting and aligning things in my documents. The current rulers using white on white are almost completely useless. You have to simply guess where you are putting tabs. Please fix this or add an option to change ruler colors.
Please try resetting the user profile, sometimes solves strange issues.
Usually it’s enough renaming/deleting the file “user/registrymodifications.xcu”, it affects all the options in Menu/Tools/Options, and the files “user/basic/dialog.xlc” and “scrip.xlc” are overwritten, additionally custom colors in “user/config/standard.soc” are lost.
I just tried resetting at your suggestion, m.a.riosv. It didn’t change anything. Note: I also just downloaded and installed LO today, so I have not actually made any changes to the settings. When I tried to change the appearance, ruler colors did not appear to be an option that could normally be altered.
Please test changing the OpenGL status on Menu/Tools/Options/LibreOffice/View.