Does anyone know why a new slide master I created in PPT won't show up as an option in the layout dropdown? I've saved, closed out, and re-opened the file, but otherwise can't figure it out...

Ultimate goal here: Have a BLANK slide layout (so that I can insert blank slides as needed so sections start on a right-hand page when printing the slides double-sided)...
If there is another alternative to doing this, then great!

(Worst case scenario: I just add blank pages to a PDF and let the page numbers fall where they will... I've already warned the client that I may not be able to get the page numbers to be odd #s for section starts... said I would try, it just may not happen... PPT isn't as easy to control for this as Word is)

THANKS!!