There isn't a direct filter for 'rag' boards but you can filter for a possible straight draw and then NOT filter for all the other types of connectedness:
(NOT (Suits on Flop All Cards of One Suit)) AND (NOT (Pair on Flop Any Pair)) AND (Connectedness on Flop Any Connectedness (Straight Draw is Possible)) AND (NOT (Connectedness on Flop All Three Cards Connected)) AND (NOT (Connectedness on Flop All Three Cards Connected With One Gap)) AND (NOT (Connectedness on Flop All Three Cards Connected With One Gap)) AND (NOT (Connectedness on Flop All Three Cards Connected With Two Gaps)) AND (NOT (Connectedness on Flop Only Two Cards Connected)) AND (NOT (Connectedness on Flop Only Two Cards Connected With One Gap)) AND (NOT (Connectedness on Flop Only Two Cards Connected With Two Gaps)) AND (NOT (Connectedness on Flop Low Hand is Possible)) AND (NOT (Connectedness on Flop Any Made Straight is Possible))
however there is a known issue with some board connected filters on Ace high boards so with this filter you will still see boards like AT9, A97. If you open a
Support Ticket we can let you know when that's fixed.