It looks like Plex is doing something weird in the web interface. Despite the playlist tracks being listed in a text format, using the browser search (CTRL-F) cannot find any of the songs in the playlist. But weirdly, it can locate the track times to the right of the track names and artist.
Is there any way to search a playlist? This is kind of crazy that Plex is doing something weird with the track and artist names to make them unsearchable using the web browser built in text search.
Lists are paged like long forum topics are paged, meaning it does not load to display all at once. So if it is a long list the parts that have not loaded to display because you have not scrolled past them will not be available for the browser search to find. many things you find on the internet are paged. There is more than just text like album art and smart playlist can load dynamically and potentially be different every time they are loaded/open