[HOW TO] force folder.pjg

[Nutul]

From the (i) help of the Thumbgen scan option in preferences (for the "+" options - Default+ and All+... what is such option in your setup?):

NOTE: Incorrect thumbnails may appear in the Library if the Album folder also contains image files and "Cover search priority" is set to Embedded.

So, it looks like @Tim Curtis was aware of the possibility of the thumbnail generator getting confused adding the functionality of images being always searched ...
I haven't investigated why, as the code seems to work perfectly, looking at what and how it does it; but if I find some time this evening I may give it a closer look.