@Joe, *
No regression, it works correctly on Windows 10 Pro 64-bit
Version: 5.1.0.2 (x64)
Build ID: ecd3574d51754b043f865cf5bafee286d24db7cc
CPU Threads: 8; OS Version: Windows 6.19; UI Render: GL;
Locale: en-US (en_US)
Clear your user profile (or copy it if you have much effort invested in
macros).
That is located by default per user in %APPDATA%\LibreOffice; e.g.
C:\Users\<yourusername>\AppData\Roaming\LibreOffice.
Just delete the folder (or rename it to hang on to anything).
A new profile will be generated on next LibreOffice launch. Should be able
to set your vertical ruler on again at that point.
Stuart