With the same APICP settings stated above, should search term 'apply' pick up 'apples'? If it does then it looks like 'y' at the end of 'appl' is being treated as a trailing vowel and being stripped off.
If search term 'wood' picks up 'woody' or search term 'ling' picks up linguist, does that mean <apicp rebuild='on'> is in action?
minwordlen set to 5
suffixlist is default
prefix is off and rebuild is on.
appl[y] matches appl[es] with defsuffrm on.
rebuild defaults to on. If it was off you could match arbitrary substrings such as "woodhaven" or "bowling".