So I loaded a genre folder and it contains several albums. One of the album is "18 Months". I've verified that there are no leading/trailing spaces in the album tag for this album.
I tried these filters to try:
ALBUM IS "18 Months" (works) ALBUM CONTAINS "18" (doesn't work. returns nothing)
According to this page (http://help.mp3tag.de/main_filter.html), my syntax for substring search should work.
I am using version 2.85.
Thanks for the help.