Copy link to clipboard
When the Navigator thumbnail doesn't match the main Loupe image after applying or hovering over a preset, the most common cause is corrupted preferences. Try resetting them:https://www.lightroomqueen.com/articles-page/how-do-i-reset-lightrooms-preferences/
LR sometimes soils its preferences file, and resetting it can fix all sorts of wonky behavior. That article explains how to restore the old preferences if resetting doesn't help.
To help others, please let us know whether this fixes the issue.