Per-page CSS edits not applying

Howdy. I use this plugin on almost every site now I love it that much. However, for some reason and for no rhyme or reason on certain sites when I go to add some per-page CSS edits they don’t render on the page or show up in the View Source code. However, if I push those edits to the general Simple CSS area they seem to work. Does anyone have any similar experience or know why this may be happening? Thanks!