The plugin does not work for me on the latest Joplin v3.1.20 (win32, prod).
No row highlighting happens in view-only mode when editing the corresponding text section in the write block.
It only highlights text on the view-only side of the MD editor when I double-tap the text.
GitHub issue: "Mark the active line of editor" feature not working on Joplin v3.1.20 · Issue #9 · ylc395/joplin-plugin-better-markdown-viewer · GitHub