Robert input buffer not working for tiger knee motion? in air Hien Ryuujin Kyaku


i’m currently working on robert trail lvl 9 and it requires to do a dp cancel into d, db, b + LK HK then jump and another d, db, b + LK HK (Hien Ryuujin Kyaku, that dive kick).
i thought i could simplify the second d, db, b + LK HK by adding. so its d, bd, b, bu + LK HK (the way you’d simplify for example leonas jump super).
if i input the directionals and hold LK + HK pushed to buffer the move it doesn’t work, if i’d do the same but only push LK or HK it does work… only the EX version will not work that way.

its only this move that doesn’t work with buffering for some reason, same method for leonas Ex super or mr. karate Ex dive kick works just fine.
checked practice mode if my inputs where wrong but they are correct.
is anyone else having the same issue? or am i doing something wrong? just wondering cause i’ve watched a vesper arcade video on youtube where he recommands tiger knee motion for this move.

i’m playing the steam version with a ps2 moded fight stick and etokki adapter.