It works fine - note, it is only a recent addition to KiXtart.

code:
"KiXtart version: "+@KIX+@CRLF
 
$aIgnore='abc','def','ghi'
 
$s='def'
If AScan($aIgnore,$s)>=0 $s+" is in the array." Else $s+" is not in the array" EndIf @CRLF
$s='foo'
If AScan($aIgnore,$s)>=0 $s+" is in the array." Else $s+" is not in the array" EndIf @CRL
Correctly ouputs:
code:
KiXtart version: 4.20
def is in the array.
foo is not in the array