This looks like a bug, when the Snap Marker effect is the last selected effect and the program is closed, it appears to corrupt the program initialisation (ini) file.
AFAICS the only way to fix this is to reset the program back to its default settings, File, Settings, Reset program settings to default . . . .
The downside is that any custom changes you have made eg file and folder paths are reset and you have to re-install all the extras again. If you elected for the extras to be left in the download folder on first installation then these will be used, which does mean they do not have to be downloaded again.