Hello,
I've encountered a bug with WACUP build #6800 (and earlier) when using some legacy plugins, in particular the NSF player NotSo Fatso (I prefer this plugin to NSFPlay because of its "Shadow to Playlist" feature.) The plugin itself has proper functionality as expected, but any changes made to the settings within the plugin are not persistent and will reset whenever WACUP is closed. This seems to affect any plugins that would normally save to the plugin.ini file in the C:\Program Files (x86)\WACUP\Plugins directory. Modifying this file manually does not change these settings in WACUP, either.